Description

Given the length and width of the ditch network, find the number of water flows that only move left and up.

Input Format

The input consists of $1$ line containing two integers $n$ and $m$.

Output Format

Output a single integer $ans$, the number of water flows. Since the answer can be large, output the result modulo $1000000007$.

3 5

56

Hint

For $30\%$ of the testdata, $1 \leq m, n \leq 10$.

For $50\%$ of the testdata, $1 \leq m, n \leq 1{,}000$.

For $80\%$ of the testdata, $1 \leq m, n \leq 50{,}000$.

For $100\%$ of the testdata, $1 \leq m, n \leq 1{,}000{,}000$.

Translated by ChatGPT 5