#include <bits/stdc++.h>
using namespace std;
const long long MAX = 2100;
const long long INF = 1.0e9;
const double EPS = 1.0e-8;
const long long MOD = 1000000007;
const double PI = acos(-1.0);
long long sum[MAX][MAX] = {0};
long long dp[MAX][MAX] = {0};
int dblcmp(double x) {
  if (fabs(x) < EPS) return 0;
  return x < 0 ? -1 : 1;
}
int main() {
  int i, j;
  long long tmp;
  for (i = 2; i < MAX; i++) dp[1][i] = sum[1][i] = 1;
  for (i = 2; i < MAX; i++) {
    tmp = 0;
    for (j = 2; j < MAX; j++) {
      dp[i][j] = dp[i][j - 1];
      tmp += dp[i - 1][j];
      if (tmp >= MOD) tmp -= MOD;
      dp[i][j] += tmp;
      if (dp[i][j] >= MOD) dp[i][j] -= MOD;
    }
  }
  for (i = 2; i < MAX; i++) {
    tmp = 0;
    for (j = 2; j < MAX; j++) {
      sum[i][j] = dp[i][j - 1];
      tmp += dp[i - 1][j];
      if (tmp >= MOD) tmp -= MOD;
      sum[i][j] += tmp - dp[i - 1][j];
      if (sum[i][j] >= MOD) sum[i][j] -= MOD;
      if (sum[i][j] < 0) sum[i][j] += MOD;
    }
  }
  for (i = 1; i < MAX; i++) {
    for (j = 0; j < MAX; j++) {
      dp[i][j] += dp[i - 1][j];
      if (dp[i][j] >= MOD) dp[i][j] -= MOD;
      sum[i][j] += sum[i - 1][j];
      if (sum[i][j] >= MOD) sum[i][j] -= MOD;
    }
  }
  int n, m;
  while (scanf("%d%d", &n, &m) != EOF) {
    long long ans = 0;
    for (i = 1; i <= n; i++) {
      for (j = 2; j <= m; j++) {
        tmp = dp[i][j] * sum[n - i + 1][j] % MOD * (m - j + 1);
        ans = (ans + tmp) % MOD;
      }
    }
    printf("%I64d\n", ans);
  }
  return 0;
}
