#include <bits/stdc++.h>
using namespace std;
struct timer {
  time_t start;
  timer() { start = clock(); }
  ~timer() {
    cerr << 1. * (clock() - start) / CLOCKS_PER_SEC << " secs" << endl;
  }
};
int n, m;
long long dp1[2010][2010];
long long sumJ[2010][2010];
long long sumI1[2010][2010];
long long dp2[2010][2010];
long long sumI2[2010][2010];
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cin >> n >> m;
  for (int j = 2; j < (m + 1); j++) {
    dp1[1][j] = dp2[1][j] = 1;
    sumJ[1][j] = sumJ[1][j - 1] + dp1[1][j];
  }
  for (int i = 2; i < (n + 1); i++)
    for (int j = 2; j < (m + 1); j++) {
      dp1[i][j] = (dp1[i][j - 1] + sumJ[i - 1][j]) % 1000000007LL;
      sumJ[i][j] = (sumJ[i][j - 1] + dp1[i][j]) % 1000000007LL;
      dp2[i][j] = (dp1[i][j] - dp1[i - 1][j] + 1000000007LL) % 1000000007LL;
    }
  for (int i = 1; i < (n + 1); i++)
    for (int j = 2; j < (m + 1); j++) {
      sumI1[i][j] = (sumI1[i - 1][j] + dp1[i][j]) % 1000000007LL;
      sumI2[i][j] = (sumI2[i - 1][j] + dp2[i][j]) % 1000000007LL;
    }
  long long ans = 0;
  for (int i = 1; i < (n + 1); i++)
    for (int j = 2; j < (m + 1); j++) {
      ans += sumI1[i][j] * sumI2[n + 1 - i][j] % 1000000007LL * (m + 1 - j);
      ans %= 1000000007LL;
    }
  cout << ans;
}
