#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, ll>
#define st first
#define nd second
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define debug false
const int MAXW = 3000 + 17;
const ll MOD = 1000 * 1000 * 1000 + 7;
ll dp[MAXW][MAXW];
ll newt[MAXW][MAXW];
int main () {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int w, h;
cin >> w >> h;
newt[0][0] = 1;
for (int i = 1; i < MAXW; i ++) {
newt[i][0] = 1;
for (int j = 1; j < MAXW; j ++) {
newt[i][j] = newt[i - 1][j - 1] + newt[i - 1][j];
newt[i][j] %= MOD;
}
}
ll wyn = 0;
dp[0][0] = 1;
for (int i = 1; i <= h; i ++) {
for (int j = 0; j <= w; j ++) {
if (j == 0) {
dp[i][j] = dp[i - 1][j];
continue;
}
if (j == 1) {
dp[i][j] = dp[i - 1][j - 1] * ll(w - (j - 1)) * 4LL;
dp[i][j] %= MOD;
dp[i][j] += dp[i - 1][j];
dp[i][j] %= MOD;
continue;
}
dp[i][j] = dp[i - 1][j - 1] * ll(w - (j - 1)) * 4LL;
dp[i][j] %= MOD;
dp[i][j] += dp[i - 1][j];
dp[i][j] %= MOD;
ll x = (w - (j - 2));
dp[i][j] += dp[i - 1][j - 2] * x * (x - 1LL)/ 2LL;
dp[i][j] %= MOD;
}
}
for (int k = 0; k <= min(w, h/2); k ++) {
int h2 = h - 2 * k;
int w2 = w - k;
ll ile = 1;
for (ll i = h; i > h2; i -= 2) {
ile *= i * (i - 1LL)/ 2LL;
ile %= MOD;
}
for (int i = 0; i <= w2; i ++) {
ll x = dp[h2][i];
x *= newt[w - i][k];
x %= MOD;
x *= ile;
x %= MOD;
wyn += x;
}
}
wyn += (MOD - 1LL);
wyn %= MOD;
cout << wyn << "\n";
return 0;
}
