#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) ((1ll << (x)))
#define debug(a, l, r) for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';
namespace math {
template<int _MOD>
struct Modint{
static const int mod = _MOD;
int v;
Modint() : v(0) {}
Modint(int _v) : v(_v) {}
Modint& operator += (const Modint &other) {
v += other.v;
if (v >= mod) v -= mod;
return *this;
}
Modint& operator -= (const Modint &other) {
v -= other.v;
if (v < 0) v += mod;
return *this;
}
Modint& operator *= (const Modint &other) {
v = 1ll * v * other.v % mod;
return *this;
}
Modint pow(int k) const {
Modint res(1), base = *this;
while (k) {
if (k & 1) res *= base;
base *= base;
k >>= 1;
}
return res;
}
Modint inv() const {return pow(mod - 2);}
Modint& operator /= (const Modint &other) {
*this *= other.inv();
return *this;
}
friend Modint operator + (Modint a, const Modint &b) {return a += b;}
friend Modint operator - (Modint a, const Modint &b) {return a -= b;}
friend Modint operator * (Modint a, const Modint &b) {return a *= b;}
friend Modint operator / (Modint a, const Modint &b) {return a /= b;}
Modint operator - () const {return Modint(0) - *this;}
friend ostream& operator << (ostream &stream, const Modint &other) {
return stream << other.v;
}
};
template <int _MOD>
struct Combinatorics{
int n;
vector<Modint<_MOD>> fact, ifact;
Combinatorics(int _n) : n(_n) {
fact.resize(n + 1, 0);
ifact.resize(n + 1, 0);
fact[0] = 1;
for (int i = 1; i <= n; ++i) fact[i] = fact[i - 1] * i;
ifact[n] = fact[n].inv();
for (int i = n - 1; i >= 0; --i) ifact[i] = ifact[i + 1] * (i + 1);
}
Modint<_MOD> C(int n, int k) {
if (k < 0 || k > n) return 0;
return fact[n] * ifact[k] * ifact[n - k];
}
};
}
using namespace math;
const int MOD = 1e9 + 7;
#define mint Modint<MOD>
const int MAXN = 3005;
int n, m;
mint dp[MAXN][MAXN];
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n >> m;
for (int i = 0; i <= n; ++i) {
for (int j = 0; j <= m; ++j) {
if (i * j == 0) {
dp[i][j] = mint(1);
continue;
}
// Không lắp thêm lều nào
dp[i][j] += dp[i - 1][j];
// Lắp thêm một lều
dp[i][j] += dp[i - 1][j - 1] * mint(4) * mint(j);
// Lắp thêm lên, xuống
if (i - 2 >= 0) dp[i][j] += dp[i - 2][j - 1] * mint(j) * mint(i - 1);
// Lắp thêm trái, phải
if (j - 2 >= 0) dp[i][j] += dp[i - 1][j - 2] * mint(j) * mint(j - 1) / 2;
}
}
cout << dp[n][m] - mint(1);
return 0;
}
