#include <iostream> #include <vector> #include <bits/stdc++.h> using namespace std; const int MODE = 1000000007; long long dp[1001][1001]; int main() { int n, m; cin >> n >> m; for(int i = 1; i <= n; i++){ for(int j = 1; j <= m; j++){ if(i == 1 && j == 1) dp[i][j] = 1; else if(i == 1) dp[i][j] = dp[i][j-1]; else if(j == 1) dp[i][j] = dp[i-1][j]; else dp[i][j] = (dp[i - 1][j] + dp[i][j - 1]) % MODE; } } cout << dp[n][m] << endl; return 0; } // 64 位输出请用 printf("%lld")