func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long md = 1000000007;   long long ans, f[2002][2002];   int n, m;   inline void solve() {     scanf( %d%d , &n, &m);     for (register int i = 1; i <= m; ++i) f[1][i] = 1;     for (register int i = 2; i <= n; ++i) {       int t = 0;       f[i][1] = 1;       for (register int j = 2; j <= m; ++j) {         (t += f[i - 1][j]) %= md;         f[i][j] = (f[i][j - 1] + t) % md;       }     }     for (register int i = 1; i <= n; ++i)       for (register int j = 2; j <= m; ++j)         (ans += (m - j + 1) * (f[i][j] - f[i - 1][j] + md) % md *                 f[n - i + 1][j] % md) %= md;     printf( %lld n , ans);   }   int main() {     ios_base::sync_with_stdio(false);     int T = 1;     for (; T--;) solve();   }   