#include <bits/stdc++.h>
using namespace std;
#define maxd 3005
#define ll long long
const int mod = 1000000007;
int H, W;
ll nomore[maxd][maxd]; //using ll just in case
ll rorem[maxd];
ll colrem[maxd][maxd];
ll facts[maxd];
ll invfacts[maxd];
ll modpow(ll base, ll pc) {
if (pc == 0) return 1LL;
if (pc & 1) {
ll tmp = modpow(base, pc-1LL);
return (tmp * base) % mod;
}
ll tmp = modpow(base, pc/2LL);
return (tmp*tmp)%mod;
}
ll inv(ll cur) {
return modpow(cur, mod-2);
}
void dofacts() { //calculate factorials and their inverses
facts[0] = 1LL;
invfacts[0] = 1LL;
for (int i = 1; i < maxd; i++) {
facts[i] = (facts[i-1]*1LL*i)%mod;
invfacts[i] = inv(facts[i]);
}
}
ll choose(int a, int b) {
//return a combination b
ll ans = facts[a] * (invfacts[a-b] * invfacts[b] % mod) % mod;
return ans % mod; // just in case
}
void calcnomore() { //do if we do no more pairing up
//f(x, 0) = f(0, x) = 1
//f(x, y) = f(x, y-1) + 4*x*f(x-1, y-1)
for (int i = 0; i <= max(H, W); i++) {
nomore[0][i] = nomore[i][0] = 1LL;
}
for (int i = 1; i <= H; i++) {
for (int j = 1; j <= W; j++) {
nomore[i][j] = nomore[i][j-1] + 0LL + 4LL * i * nomore[i-1][j-1] % mod;
nomore[i][j] %= mod;
}
}
}
void calcrorem() { //calculate how many ways you can do x row removals
for (int i = 0; i <= H; i++) {
rorem[i] = 0LL; //incase we break
}
ll runprod = 1LL; //the running product
rorem[0] = 1LL; //only one way to remove nothing
for (int i = 1; i <= H; i++) {
if (2*i > W) break; //cannot take all of this
runprod = (runprod * choose(W - i*2 + 2, 2))%mod;
ll cur = (runprod * choose(H, i))%mod;
rorem[i] = cur;
}
}
void calccolrem() {
//calc how many ways you can do y column removals,
// given you already did x row removals
for (int i = 0; i <= H; i++) {
for (int j = 0; j <= W; j++) {
colrem[i][j] = 0LL; //same idea, set to zero in case we break
}
}
for (int i = 0; i <= H; i++) {
if (2*i > W) break;
int h = H-i;
int w = W - 2*i;
//little h and w represent slightly changed values
ll runprod = 1LL;
colrem[i][0] = 1LL; //one way to remove nothing
for (int j = 1; j <= W; j++) {
if (2*i + j > W || i + 2*j > H) break; //something is deficient
runprod = (runprod * choose(h - j*2 + 2, 2))%mod;
ll cur =(runprod * choose(w, j))%mod;
colrem[i][j] = cur;
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> H >> W;
dofacts();
calcnomore();
calcrorem();
calccolrem();
ll ans = 0LL;
//looking at doing x row rem and y col rem
for (int i = 0; i <= H; i++) {
for (int j = 0; j <= W; j++) {
ll cur = (rorem[i] * colrem[i][j]) % mod;
if (cur == 0LL) continue; //do not get index out of bounds
cur = (cur * nomore[H - i - 2*j][W - 2*i - j]) % mod;
// cout << i << " " << j << ": " << cur << endl;
ans = (ans + cur) % mod;
}
}
// cout << "ans: ";
ans = (ans + mod - 1LL)%mod; //subtract out the nothing placed case
cout << ans << endl;
cin >> ans;
}
//probably some dp
