#include <bits/stdc++.h>
using namespace std;
const int N = 2005, Mod = 1000000007;
int f[N][N], g[N][N], sum, Ans, n, m;
inline int Read() {
  int t = 0, f = 1;
  char c = getchar();
  for (; c > 57 || c < 48; c = getchar())
    if (c == '-') f = -1;
  for (; c > 47 && c < 58; c = getchar()) t = (t << 1) + (t << 3) + c - 48;
  return t * f;
}
inline int Add(int &x, int y) { x = (x + y % Mod) % Mod; }
int main() {
  n = Read(), m = Read();
  for (int i = 1; i <= n; i++, sum = 0)
    for (int j = 2; j <= m; j++) {
      Add(f[i][j], g[i - 1][j] + 1);
      Add(sum, f[i][j]), Add(g[i][j], g[i][j - 1] + sum);
    }
  for (int i = 1; i <= n; i++)
    for (int j = 2; j <= m; j++)
      Add(Ans, 1ll * f[i][j] * (g[n - i][j] - f[n - i][j] + 1) % Mod *
                   (m - j + 1) % Mod);
  printf("%d\n", Ans);
}
