/* 2013-07-26 11:05:35.465811 */#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <cassert>
#include <sstream>
#include <bitset>
#include <numeric>
#include <climits>
#include <string>
#include <cctype>
#include <ctime>
#include <iomanip>
#include <cmath>
#include <vector>
#include <queue>
#include <list>
#include <map>
#include <set>

#define MM(a, b) memset(a, b, sizeof(a))
#define MP(a, b) make_pair(a, b)
#define PB(a) push_back(a)

using namespace std;

const int maxn = 2111;
const int maxm = 111;
const int INF = 0x3f3f3f3f;
const double eps = 1e-8;

int n, m;

void solve(){}

const long long mod = 1000000007;

long long F[maxn][maxn];
long long G[maxn][maxn];

int main(){
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; ++i){
        long long tot = 0;
        for (int j = 2; j <= m; j++){
            F[i][j] = (1 + G[i - 1][j]) % mod;
            tot = (tot + F[i][j]) % mod;
            G[i][j] = (G[i][j - 1] + tot) % mod;
        }
    }
    long long ret = 0;
    for (int i = 1; i <= n; ++i)
        for (int j = 2; j <= m; j++){
            ret = (ret + F[i][j] * ((G[n - i][j] - F[n - i][j] + 1ll) % mod + mod) % mod * (m - j + 1) % mod) % mod;
        }
    cout<<ret<<endl;
}
