CSES - Counting Tilings
  • Time limit: 1.00 s
  • Memory limit: 512 MB
Your task is to count the number of ways you can fill an $n \times m$ grid using $1 \times 2$ and $2 \times 1$ tiles.

Input

The only input line has two integers $n$ and $m$.

Output

Print one integer: the number of ways modulo $10^9+7$.

Constraints
  • $1 \le n \le 10$
  • $1 \le m \le 1000$
Example

Input:
4 7

Output:
781