#include <bits/stdc++.h>
using namespace std;
long long N, M, prime = 1000000007;
long long dp[2005][2005] = {0};
int main() {
  FILE *INPUT = stdin;
  fscanf(INPUT, "%d%d", &N, &M);
  int i1 = 0, i2 = 0, i3 = 0;
  long long val1 = 0, val2 = 0, val3 = 0;
  for (i1 = 1; i1 <= N; ++i1) {
    val1 = 0;
    val2 = 1;
    for (i2 = 2; i2 <= M; ++i2) {
      val1 = (val1 + dp[i1 - 1][i2]) % prime;
      val2 = (val1 + val2) % prime;
      dp[i1][i2] = val2;
    }
  }
  long long caves = 0;
  for (i1 = 2; i1 <= M; ++i1) {
    val1 = 0;
    val2 = 0;
    for (i2 = 1; i2 <= N; ++i2) {
      val1 = dp[i2][i1] - dp[i2 - 1][i1];
      val2 = (val2 + val1 * dp[N - i2 + 1][i1]) % prime;
    }
    val2 = (val2 * (M - i1 + 1)) % prime;
    caves = (caves + val2) % prime;
  }
  printf("%d\n", (prime + caves) % prime);
  return 0;
}
