#include <bits/stdc++.h>
using namespace std;
const int maxn = 2 * 1000 + 10, maxm = (1 << 17), mod = (int)1e9 + 7,
          hash = 701, maxim = (1 << 24) + 10, inf = (1 << 29) + 3;
const double pi = 3.14159265359, ee = 2.71828;
long long d[2][maxn][maxn], dp[2][maxn][maxn], ans;
void update(int x, int p, int ind, long long val) {
  for (int i = ind; i < maxn; i += (i & -i)) d[p][x][i] += val, d[p][x][i];
}
long long query(int x, int p, int ind) {
  long long sum = 0;
  for (int i = ind; i; i -= (i & -i)) sum += d[p][x][i];
  return sum % mod;
}
int main() {
  ios::sync_with_stdio(0);
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++)
    for (int j = 2; j <= m; j++) {
      dp[1][i][j] =
          (query(i - 1, 0, j) * j - query(i - 1, 1, j) + 1 + mod) % mod;
      update(i, 0, j, dp[1][i][j]),
          update(i, 1, j, (dp[1][i][j] * (j - 1)) % mod);
      dp[0][i][j] =
          (query(i - 1, 0, j - 1) * j - query(i - 1, 1, j - 1) + 1 + mod) % mod;
    }
  for (int i = 1; i <= n; i++)
    for (int j = 2; j <= m; j++)
      ans += ((dp[0][i][j] * dp[1][n - i + 1][j]) % mod) * (m - j + 1),
          ans %= mod;
  cout << ans << endl;
  return 0;
}
