#include <bits/stdc++.h>
using namespace std;
long long cumdp[2005];
long long cumpd[2005];
long long dp[2005][2005];
long long pd[2005][2005];
const long long mod = 1e9 + 7;
int main() {
  long long n, m;
  cin >> n >> m;
  for (int width = 2; width <= m; width++) {
    dp[1][width] = 1;
    pd[1][width] = 1;
  }
  for (int len = 2; len <= n; len++) {
    long long sum = 0;
    for (int width = 2; width <= m; width++) {
      sum += dp[len - 1][width];
      sum %= mod;
      dp[len][width] = dp[len][width - 1] + sum;
      pd[len][width] = dp[len][width] - dp[len - 1][width];
    }
  }
  long long ans = 0;
  for (int base = 1; base <= m; base++) {
    for (int len = 1; len <= n; len++) {
      cumdp[len] = cumdp[len - 1] + dp[len][base];
      cumdp[len] %= mod;
      cumpd[len] = cumpd[len - 1] + pd[len][base];
      cumpd[len] %= mod;
    }
    long long cur = 0;
    for (int cen = 1; cen <= n; cen++) {
      cur += (cumdp[cen] * cumpd[n - cen + 1]) % mod;
      cur %= mod;
    }
    cur *= (m - base + 1);
    cur %= mod;
    ans += cur;
    ans %= mod;
  }
  cout << ans << "\n";
}
