27579번 - Fading Wind 다국어

문제

You're competing in an outdoor paper airplane flying contest, and you want to predict how far your paper airplane will fly. Your design has a fixed factor $k,ドル such that if the airplane's velocity is at least $k,ドル it will rise. If its velocity is less than $k$ it will descend.

Here is how your paper airplane will fly:

• You start by throwing your paper airplane with a horizontal velocity of $v$ at a height of $h$. There is an external wind blowing with a strength of $s$.
• While $h > 0,ドル repeat the following sequence:
  • Increase $v$ by $s$. Then, decrease $v$ by $\max(1, \left\lfloor \frac{v}{10} \right\rfloor)$. Note that $\left\lfloor \frac{v}{10} \right\rfloor$ is the value of $\frac{v}{10},ドル rounded down to the nearest integer if it is not an integer.
  • If $v \ge k,ドル increase $h$ by one.
  • If 0ドル < v < k,ドル decrease $h$ by one. If $h$ is zero after the decrease, set $v$ to zero.
  • If $v \le 0,ドル set $h$ to zero and $v$ to zero.
  • Your airplane now travels horizontally by $v$ units.
  • If $s > 0,ドル decrease it by 1ドル$.

Compute how far the paper airplane travels horizontally.

입력

The single line of input contains four integers $h,ドル $k,ドル $v,ドル and $s$ $(1 \le h, k, v, s \le 10^3),ドル where $h$ is your starting height, $k$ is your fixed factor, $v$ is your starting velocity, and $s$ is the strength of the wind.

출력

Output a single integer, which is the distance your airplane travels horizontally. It can be shown that this distance is always an integer.

제한

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