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##Perl (no +/-, no tie-breakers, 29 chars)##

s!!xx!;s!x!$"x<>!eg;say y!!!c

As a bonus, you can make the code sum more than two numbers by adding more xs to the s!!xx!.

Alternatively, here are two 21-char solutions with 1 and 3 tie-breakers respectively

say length$"x<>.$"x<>
say log exp(<>)*exp<>

Note: These solutions use the say function, available since Perl 5.10.0 with the -E command line switch or with use 5.010. See the edit history of this answer for versions that work on older perls.

How does the solution with no tie-breakers work?

• s!!xx! is a regexp replacement operator, operating by default on the $_ variable, which replaces the empty string with the string xx. (Usually / is used as the regexp delimiter in Perl, but really almost any character can be used. I chose ! since it's not a tie-breaker.) This is just a fancy way of prepending "xx" to $_ — or, since $_ starts out empty (undefined, actually), it's really a way to write $_ = "xx" without using the equals sign (and with one character less, too).

• `s!x!$"x!eg` is another regexp replacement, this time replacing each `x` in `$_` with the value of the expression `$" x `. (The `g` switch specifies global replacement, `e` specifies that the replacement is to be evaluated as Perl code instead of being used as a literal string.) `$"` is a [special variable](http://perldoc.perl.org/perlvar.html#$LIST_SEPARATOR) whose default value happens to be a single space; using it instead of `" "` saves one char. (Any other variable known to have a one-character value, such as `$&` or `$/`, would work equally well here, except that using `$/` would cost me a tie-breaker.)

  The `` [line input operator](http://perldoc.perl.org/perlop.html#I%2fO-Operators), in scalar context, reads one line from standard input and returns it. The `x` before it is the Perl [string repetition operator](http://perldoc.perl.org/perlop.html#Multiplicative-Operators), and is really the core of this solution: it returns its left operand (a single space character) repeated the number of times given by its right operand (the line we just read as input).

• y!!!c is just an obscure way to (ab)use the transliteration operator to count the characters in a string ($_ by default, again). I could've just written say length, but the obfuscated version is one character shorter. :)

##Perl (no +/-, no tie-breakers, 29 chars)##

s!!xx!;s!x!$"x<>!eg;say y!!!c

As a bonus, you can make the code sum more than two numbers by adding more xs to the s!!xx!.

Alternatively, here are two 21-char solutions with 1 and 3 tie-breakers respectively

say length$"x<>.$"x<>
say log exp(<>)*exp<>

Note: These solutions use the say function, available since Perl 5.10.0 with the -E command line switch or with use 5.010. See the edit history of this answer for versions that work on older perls.

How does the solution with no tie-breakers work?

• s!!xx! is a regexp replacement operator, operating by default on the $_ variable, which replaces the empty string with the string xx. (Usually / is used as the regexp delimiter in Perl, but really almost any character can be used. I chose ! since it's not a tie-breaker.) This is just a fancy way of prepending "xx" to $_ — or, since $_ starts out empty (undefined, actually), it's really a way to write $_ = "xx" without using the equals sign (and with one character less, too).

• `s!x!$"x!eg` is another regexp replacement, this time replacing each `x` in `$_` with the value of the expression `$" x `. (The `g` switch specifies global replacement, `e` specifies that the replacement is to be evaluated as Perl code instead of being used as a literal string.) `$"` is a [special variable](http://perldoc.perl.org/perlvar.html#$LIST_SEPARATOR) whose default value happens to be a single space; using it instead of `" "` saves one char. (Any other variable known to have a one-character value, such as `$&` or `$/`, would work equally well here, except that using `$/` would cost me a tie-breaker.)

  The `` [line input operator](http://perldoc.perl.org/perlop.html#I%2fO-Operators), in scalar context, reads one line from standard input and returns it. The `x` before it is the Perl [string repetition operator](http://perldoc.perl.org/perlop.html#Multiplicative-Operators), and is really the core of this solution: it returns its left operand (a single space character) repeated the number of times given by its right operand (the line we just read as input).

• y!!!c is just an obscure way to (ab)use the transliteration operator to count the characters in a string ($_ by default, again). I could've just written say length, but the obfuscated version is one character shorter. :)

##Perl (no +/-, no tie-breakers, 28 chars)##

s!!xx!;s!x!1x<>!eg;say y!!!c

As a bonus, you can make the code sum more than two numbers by adding more xs to the s!!xx!.

Alternatively, here are two 21-char solutions with 1 and 3 tie-breakers respectively

say length$"x<>.$"x<>
say log exp(<>)*exp<>

Note: These solutions use the say function, available since Perl 5.10.0 with the -E command line switch or with use 5.010. See the edit history of this answer for versions that work on older perls.

How does the solution with no tie-breakers work?

• s!!xx! is a regexp replacement operator, operating by default on the $_ variable, which replaces the empty string with the string xx. (Usually / is used as the regexp delimiter in Perl, but really almost any character can be used. I chose ! since it's not a tie-breaker.) This is just a fancy way of prepending "xx" to $_ — or, since $_ starts out empty (undefined, actually), it's really a way to write $_ = "xx" without using the equals sign (and with one character less, too).

• `s!x!1x!eg` is another regexp replacement, this time replacing each `x` in `$_` with the value of the expression `1 x `. (The `g` switch specifies global replacement, `e` specifies that the replacement is to be evaluated as Perl code instead of being used as a literal string.)

  The `` [line input operator](http://perldoc.perl.org/perlop.html#I%2fO-Operators), in scalar context, reads one line from standard input and returns it. The `x` before it is the Perl [string repetition operator](http://perldoc.perl.org/perlop.html#Multiplicative-Operators), and is really the core of this solution: it returns its left operand (the number `1`) repeated the number of times given by its right operand (the line we just read as input).

• y!!!c is just an obscure way to (ab)use the transliteration operator to count the characters in a string ($_ by default, again). I could've just written say length, but the obfuscated version is one character shorter. :)

##Perl (no +/-, no tie-breakers, 29 chars)##

s!!xx!;s!x!$"x<>!eg;say y!!!c

As a bonus, you can make the code sum more than two numbers by adding more xs to the s!!xx!.

Alternatively, here are two 21-char solutions with 1 and 3 tie-breakers respectively

say length$"x<>.$"x<>
say log exp(<>)*exp<>

Note: These solutions use the say function, available since Perl 5.10.0 with the -E command line switch or with use 5.010. See the edit history of this answer for versions that work on older perls.

How does the solution with no tie-breakers work?

• s!!xx! is a regexp replacement operator, operating by default on the $_ variable, which replaces the empty string with the string xx. (Usually / is used as the regexp delimiter in Perl, but really almost any character can be used. I chose ! since it's not a tie-breaker.) This is just a fancy way of prepending "xx" to $_ — or, since $_ starts out empty (undefined, actually), it's really a way to write $_ = "xx" without using the equals sign (and with one character less, too).

• `s!x!$"x!eg` is another regexp replacement, this time replacing each `x` in `$_` with the value of the expression `$" x `. (The `g` switch specifies global replacement, `e` specifies that the replacement is to be evaluated as Perl code instead of being used as a literal string.) `$"` is a [special variable](http://perldoc.perl.org/perlvar.html#$LIST_SEPARATOR) whose default value happens to be a single space; using it instead of `" "` saves one char. (Any other variable known to have a one-character value, such as `$&` or `$/`, would work equally well here, except that using `$/` would cost me a tie-breaker.)

  The `` [line input operator](http://perldoc.perl.org/perlop.html#I%2fO-Operators), in scalar context, reads one line from standard input and returns it. The `x` before it is the Perl [string repetition operator](http://perldoc.perl.org/perlop.html#Multiplicative-Operators), and is really the core of this solution: it returns its left operand (a single space character) repeated the number of times given by its right operand (the line we just read as input).

• y!!!c is just an obscure way to (ab)use the transliteration operator to count the characters in a string ($_ by default, again). I could've just written say length, but the obfuscated version is one character shorter. :)

##Perl (no +/-, no tie-breakers, 29 chars)##

s!!xx!;s!x!$"x<>!eg;say y!!!c

As a bonus, you can make the code sum more than two numbers by adding more xs to the s!!xx!.

Alternatively, here are two 21-char solutions with 1 and 3 tie-breakers respectively

say length$"x<>.$"x<>
say log exp(<>)*exp<>

Note: These solutions use the say function, available since Perl 5.10.0 with the -E command line switch or with use 5.010. See the edit history of this answer for versions that work on older perls.

How does the solution with no tie-breakers work?

• s!!xx! is a regexp replacement operator, operating by default on the $_ variable, which replaces the empty string with the string xx. (Usually / is used as the regexp delimiter in Perl, but really almost any character can be used. I chose ! since it's not a tie-breaker.) This is just a fancy way of prepending "xx" to $_ — or, since $_ starts out empty (undefined, actually), it's really a way to write $_ = "xx" without using the equals sign (and with one character less, too).

• `s!x!$"x!eg` is another regexp replacement, this time replacing each `x` in `$_` with the value of the expression `$" x `. (The `g` switch specifies global replacement, `e` specifies that the replacement is to be evaluated as Perl code instead of being used as a literal string.) `$"` is a [special variable](http://perldoc.perl.org/perlvar.html#$LIST_SEPARATOR) whose default value happens to be a single space; using it instead of `" "` saves one char. (Any other variable known to have a one-character value, such as `$&` or `$/`, would work equally well here, except that using `$/` would cost me a tie-breaker.)

  The `` [line input operator](http://perldoc.perl.org/perlop.html#I%2fO-Operators), in scalar context, reads one line from standard input and returns it. The `x` before it is the Perl [string repetition operator](http://perldoc.perl.org/perlop.html#Multiplicative-Operators), and is really the core of this solution: it returns its left operand (a single space character) repeated the number of times given by its right operand (the line we just read as input).

• y!!!c is just an obscure way to (ab)use the transliteration operator to count the characters in a string ($_ by default, again). I could've just written say length, but the obfuscated version is one character shorter. :)

##Perl (no +/-, no tie-breakers, 28 chars)##

s!!xx!;s!x!1x<>!eg;say y!!!c

As a bonus, you can make the code sum more than two numbers by adding more xs to the s!!xx!.

Alternatively, here are two 21-char solutions with 1 and 3 tie-breakers respectively

say length$"x<>.$"x<>
say log exp(<>)*exp<>

Note: These solutions use the say function, available since Perl 5.10.0 with the -E command line switch or with use 5.010. See the edit history of this answer for versions that work on older perls.

How does the solution with no tie-breakers work?

• s!!xx! is a regexp replacement operator, operating by default on the $_ variable, which replaces the empty string with the string xx. (Usually / is used as the regexp delimiter in Perl, but really almost any character can be used. I chose ! since it's not a tie-breaker.) This is just a fancy way of prepending "xx" to $_ — or, since $_ starts out empty (undefined, actually), it's really a way to write $_ = "xx" without using the equals sign (and with one character less, too).

• `s!x!1x!eg` is another regexp replacement, this time replacing each `x` in `$_` with the value of the expression `1 x `. (The `g` switch specifies global replacement, `e` specifies that the replacement is to be evaluated as Perl code instead of being used as a literal string.)

  The `` [line input operator](http://perldoc.perl.org/perlop.html#I%2fO-Operators), in scalar context, reads one line from standard input and returns it. The `x` before it is the Perl [string repetition operator](http://perldoc.perl.org/perlop.html#Multiplicative-Operators), and is really the core of this solution: it returns its left operand (the number `1`) repeated the number of times given by its right operand (the line we just read as input).

• y!!!c is just an obscure way to (ab)use the transliteration operator to count the characters in a string ($_ by default, again). I could've just written say length, but the obfuscated version is one character shorter. :)