#include <bits/stdc++.h>
using namespace std;
const int MOD = 1000000007;
typedef long long ll;
int add(int a, int b){
return (a+b)%MOD;
}
int mul(int a, int b){
return ((ll)a*b)%MOD;
}
int pw(int a, int b){
if(b == 0) return 1;
int res = pw(a, b/2);
res = mul(res, res);
if(b%2) res = mul(res, a);
return res;
}
int inv[3005];
int fact[3005];
int dp[3005][3005];
int bin(int n, int k){
if(n < 0 || k < 0 || n < k) return 0;
int res = fact[n];
res = mul(res, inv[n-k]);
res = mul(res, inv[k]);
return res;
}
int solve(int h, int w){
if(h < 0 || w < 0) return 0;
if(h == 0 || w == 0) return 1;
if(dp[h][w]) return dp[h][w];
/// hor. par
dp[h][w] = add(dp[h][w], mul(solve(h-1, w-2), w*(w-1)/2));
/// ver. par
dp[h][w] = add(dp[h][w], mul(solve(h-2, w-1), mul(w, h-1)));
/// samo jedan
dp[h][w] = add(dp[h][w], mul(4, mul(solve(h-1, w-1), w)));
/// nista
dp[h][w] = add(dp[h][w], solve(h-1, w));
return dp[h][w];
}
int main(){
ios_base::sync_with_stdio(false);
fact[0] = inv[0] = 1;
for(int i=1; i<=3000; i++){
fact[i] = mul(fact[i-1], i);
inv[i] = pw(fact[i], MOD-2);
}
int h, w;
cin >> h >> w;
cout << add(solve(h, w), MOD-1);
return 0;
}
