20796번 - Integers and Ranges 다국어

문제

Isaac has a decimal integer $\overline{a_1 a_2 \dots a_n},ドル possibly with leading zeroes. He knows that for $m$ ranges $[l_1, r_1], [l_2, r_2], \dots, [l_m, r_m],ドル it holds that $a_{l_i} \times a_{l_i + 1} \times \dots \times a_{r_i} \bmod 9 = 0$. Find the number of valid integers $\overline{a_1 a_2 \dots a_n},ドル modulo $(10^9+7)$.

입력

The input consists of several test cases and is terminated by end-of-file.

The first line of each test case contains two integers $n$ and $m$.

The $i$th of the following $m$ lines contains two integers $l_i$ and $r_i$.

출력

For each test case, print an integer which denotes the result.

제한

• 1ドル \leq n, m \leq 10^3$
• 1ドル \leq l_i \leq r_i \leq n$
• There are at most 100ドル$ test cases.

힌트