#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2010;
const int MAXM = 2010;
const long long MOD = int(1e+9) + 7;
int N, M;
long long dp[MAXN][MAXM], prefix1[MAXN][MAXM], prefix2[MAXN][MAXM];
int main() {
  scanf("%d%d", &N, &M);
  int i, j;
  for (i = 1; i <= M - 1; i++) {
    dp[0][i] = 0;
    dp[1][i] = 1;
  }
  for (i = 2; i <= N; i++) {
    prefix1[i - 1][0] = 0;
    for (j = 1; j <= M - 1; j++)
      prefix1[i - 1][j] = (prefix1[i - 1][j - 1] + dp[i - 1][j]) % MOD;
    prefix2[i - 1][0] = 0;
    for (j = 1; j <= M - 1; j++)
      prefix2[i - 1][j] = (prefix2[i - 1][j - 1] + prefix1[i - 1][j]) % MOD;
    for (j = 1; j <= M - 1; j++) dp[i][j] = (prefix2[i - 1][j] + 1) % MOD;
  }
  long long ans = 0;
  for (i = 1; i <= N; i++)
    for (j = 1; j <= M - 1; j++) {
      long long Q = dp[i][j] * (dp[N + 1 - i][j] - dp[N - i][j] + MOD) % MOD;
      ans = (ans + Q * (M - j)) % MOD;
    }
  cout << ans << endl;
}
