#include <bits/stdc++.h>
using namespace std;
long long modu = 1000000007LL;
long long dp_freecnt[2050][2050][2];
long long Get(int space, int freedom, int left_tied = 0) {
  if (space < 0) return 0LL;
  long long& alias = dp_freecnt[space][freedom][left_tied];
  if (alias != -1LL) return alias;
  alias = 1LL;
  if (freedom) alias += Get(space, freedom - 1, 0);
  alias %= modu;
  if (!left_tied) alias += Get(space - 1, freedom, left_tied);
  alias %= modu;
  alias += Get(space - 1, freedom, 1);
  alias %= modu;
  return alias;
}
int main() {
  int row, col;
  cin >> row >> col;
  for (int(i) = 0; (i) < (2050); ++(i))
    for (int(j) = 0; (j) < (2050); ++(j))
      for (int(k) = 0; (k) < (2); ++(k)) dp_freecnt[i][j][k] = -1LL;
  long long res = 0LL;
  for (int(i) = 0; (i) < (row); ++(i)) {
    for (int jar = 1; jar < col; ++jar) {
      long long cnt = (long long)(col - jar);
      long long atas = 1LL;
      if (i) {
        atas += Get(jar - 1, i - 1);
        atas %= modu;
      }
      long long bawah = 1LL;
      if (i != row - 1) {
        int sisa = row - i - 2;
        long long mult = Get(jar - 2, sisa) * 2LL - Get(jar - 3, sisa);
        mult %= modu;
        while (mult < modu) mult += modu;
        bawah += mult;
        bawah %= modu;
      }
      cnt *= atas;
      cnt %= modu;
      cnt *= bawah;
      cnt %= modu;
      res += cnt;
      res %= modu;
    }
  }
  cout << res << endl;
}
