#include <bits/stdc++.h>
using namespace std;
template <typename T>
void r1(T &x) {
  x = 0;
  char c(getchar());
  int f(1);
  for (; c < '0' || c > '9'; c = getchar())
    if (c == '-') f = -1;
  for (; '0' <= c && c <= '9'; c = getchar()) x = (x * 10) + (c ^ 48);
  x *= f;
}
const int mod = 1e9 + 7;
template <int mod>
struct typemod {
  int z;
  typemod(int a = 0) : z(a) {}
  inline int inc(int a, int b) const {
    return a += b - mod, a + ((a >> 31) & mod);
  }
  inline int dec(int a, int b) const { return a -= b, a + ((a >> 31) & mod); }
  inline int mul(int a, int b) const { return 1ll * a * b % mod; }
  typemod<mod> operator+(const typemod<mod> &x) const {
    return typemod(inc(z, x.z));
  }
  typemod<mod> operator-(const typemod<mod> &x) const {
    return typemod(dec(z, x.z));
  }
  typemod<mod> operator*(const typemod<mod> &x) const {
    return typemod(mul(z, x.z));
  }
  typemod<mod> &operator+=(const typemod<mod> &x) {
    *this = *this + x;
    return *this;
  }
  typemod<mod> &operator-=(const typemod<mod> &x) {
    *this = *this - x;
    return *this;
  }
  typemod<mod> &operator*=(const typemod<mod> &x) {
    *this = *this * x;
    return *this;
  }
  int operator==(const typemod<mod> &x) const { return x.z == z; }
  int operator!=(const typemod<mod> &x) const { return x.z != z; }
};
template <typename T, typename... Args>
inline void r1(T &t, Args &...args) {
  r1(t);
  r1(args...);
}
const int maxn = 2e3 + 5;
const int maxm = maxn << 1;
typemod<mod> f[maxn][maxn], g[maxn][maxn];
int n, m;
signed main() {
  int i, j;
  r1(n, m);
  for (i = 2; i <= m; ++i) f[1][i] = 1;
  for (i = 2; i <= n; ++i) {
    for (j = 2; j <= m; ++j) {
      f[i][j] = f[i - 1][j] + f[i][j - 1] + f[i][j - 1] - f[i][j - 2];
    }
  }
  for (i = 1; i <= n; ++i) {
    for (j = 2; j <= m; ++j) g[i][j] = g[i - 1][j] + f[i][j];
  }
  typemod<mod> res(0);
  for (i = 1; i <= n; ++i)
    for (j = 2; j <= m; ++j) res += f[i][j] * g[n - i + 1][j] * (m - j + 1);
  printf("%d\n", res.z);
  return 0;
}
