//#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
#include <set>
//#include <queue>
//#include <stack>
#include <cstring>
#include <cassert>
using namespace std;
#ifdef LOCAL_DEBUG
#include <local_debug.h>
#define DEBUG(...) DBG2::print(#__VA_ARGS__, __LINE__, __VA_ARGS__)
#else
#define DEBUG(...)
#endif
#define SZ(a) int((a).size())
#define REP(i,n) for(int i=0,_n=(n);i<_n;++i)
#define FOR(i,a,b) for(int i=(a),_b=(b);i<=_b;++i)
typedef long long llong;
typedef vector<int> VI;
typedef vector<VI> VVI;
const int MOD = 1e9 + 7;
llong Choose2(int n) {
return n * 1LL * (n-1) / 2;
}
int memo[3004][3004];
int go(int R, int C) {
assert(R >= 0 && C >= 0);
// if (R < 0 || C < 0) return 0;
if (R == 0 || C == 0) return 1;
int& res = memo[R][C];
if (res < 0) {
res = go(R-1, C); // do not place a tent in last row
// place single tent in last row and one of the remaining columns (and
// no other in same column
llong add = go(R-1, C-1) * 4LL * C;
res = (res + add) % MOD;
// place two tents in the last row
if (C >= 2) {
add = go(R-1, C-2) * Choose2(C);
res = (res + add) % MOD;
}
// place two tents in the same column, one of which is in last row
if (R >= 2) {
add = go(R-2, C-1) * 1LL * (R-1) * C;
res = (res + add) % MOD;
}
}
return res;
}
int main(int argc, char* argv[]) {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int R, C;
cin >> R >> C;
memset(memo, -1, sizeof(memo));
int res = go(R, C);
// remove case where no tent was placed
res = (res + MOD - 1) % MOD;
cout << res << '\n';
return 0;
}
