#include <iostream>
#define MOD 1000000007
using namespace std;
int dp_ind[3001][3001];
int dp_ttl[3001][3001];
int dp_se[3001][3001];
int col[3001];
int main () {
int n, m;
cin >> n >> m;
int row;
for (int i=1; i<=n; i++) {
row = 0;
for (int j=1; j<=m; j++) {
dp_se[i][j] = dp_ttl[i-1][j-1]+1;
dp_ind[i][j] = (4ll*dp_se[i][j]+row+col[j])%MOD;
dp_ttl[i][j] = (1ll*dp_ttl[i-1][j]+dp_ttl[i][j-1]-dp_ttl[i-1][j-1]+dp_ind[i][j])%MOD;
row = (1ll*row+dp_se[i][j])%MOD;
col[j] = (1ll*col[j]+dp_se[i][j])%MOD;
}
}
cout << dp_ttl[n][m] << endl;
}
