#include <bits/stdc++.h>
using namespace std;
#define int long long
const int mod = 1e9+7;
vector<int> fact(1e5+1);
vector<int> inv(1e5+1);
int fpow(int n, int k){
//n^k
if(k == 0) return 1;
int r = 1;
if(k%2 == 1){
r = n;
}
int f = fpow(n, k/2);
return f*f%mod*r%mod;
}
int C(int n, int k){
return fact[n] * inv[k]%mod * inv[n-k]%mod;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int h, w; cin >> h >> w;
fact[0] = 1;
inv[0] = 1;
int c = 1;
for(int i = 1; i <= 1e5; i++){
c *= i;
c%=mod;
fact[i] = c;
inv[i] = fpow(fact[i], mod-2);
}
vector<int> pref(1e5+1);
pref[1] = 1;
pref[0] = 1;
for(int i = 2; i <= 1e5; i++){
pref[i] = ((i * (i-1))/2%mod * pref[i-2])%mod;
}
vector<vector<int>> precomp(3001, vector<int>(3001));
for (int i = 0; i <= 3000; i++) precomp[i][0] = 1;
for (int j = 0; j <= 3000; j++) precomp[0][j] = 1;
for(int i = 1; i <= 3000; i++){
for(int y = 1; y <= 3000; y++){
precomp[i][y] = precomp[i-1][y] + precomp[i-1][y-1] * (4*y)%mod;
precomp[i][y]%=mod;
}
}
int ans = 0;
for(int i = 0; i <= h; i++){
for(int y = 0; y <= w; y++){
//h vertical
//w hori
if(w - i - y*2 < 0 || h - i*2 - y < 0) continue;
int ns = C(w, i) * (pref[h] * fpow(pref[h - i*2], mod-2)%mod)%mod;
if(i == 0){
ns = 1;
}
int sisa = w-i;
int colsisa = h-i*2;
if(y > 0){
ns = ns * C(colsisa, y)%mod * pref[sisa]%mod * fpow(pref[sisa - y*2], mod-2)%mod;
}
sisa -= y*2;
colsisa -= y;
if(min(sisa, colsisa) > 0){
ns = ns*(precomp[max(sisa, colsisa)][min(sisa, colsisa)]+mod)%mod;
}
ans += ns;
ans%=mod;
}
}
cout << ans-1 << "\n";
return 0;
}
