#include <bits/stdc++.h>
#define SZ(v) ((int)(v).size())
using namespace std;
using ll = long long;
template<typename... Args>
void read(Args&... args)
{
((cin >> args), ...);
}
template<typename T>
void read(vector<T> &vec)
{
for (auto &v : vec) read(v);
}
void write() {}
template<typename H, typename... T>
void write(const H &h, const T&... t)
{
cout << h;
if (sizeof...(t)) {cout << ' '; write(t...);}
}
template<typename T>
void write(const vector<T> &vec)
{
if (SZ(vec) == 0) return;
write(vec[0]);
for (int i(1); i < SZ(vec); ++i)
{cout << ' '; write(vec[i]);}
}
template<typename... Args>
void writeln(Args... args)
{
write(args...); cout << '\n';
}
template<const int32_t MOD>
struct ModInt {
long long x;
ModInt() : x(0) {}
ModInt(long long u) : x(u) { x %= MOD; if (x < 0) x += MOD;}
friend bool operator == (const ModInt& a, const ModInt& b) { return a.x == b.x; }
friend bool operator != (const ModInt& a, const ModInt& b) { return a.x != b.x; }
friend bool operator < (const ModInt& a, const ModInt& b) { return a.x < b.x; }
friend bool operator > (const ModInt& a, const ModInt& b) { return a.x > b.x; }
friend bool operator <= (const ModInt& a, const ModInt& b) { return a.x <= b.x; }
friend bool operator >= (const ModInt &a, const ModInt& b) { return a.x >= b.x; }
static ModInt sign(long long k) { return ((k & 1) ? ModInt(MOD-1) : ModInt(1)); }
ModInt& operator += (const ModInt& m) { x += m.x; if(x >= MOD) x -= MOD; return *this; }
ModInt& operator -= (const ModInt& m) { x -= m.x; if(x < 0LL) x += MOD; return *this; }
ModInt& operator *= (const ModInt& m) { x = (1LL * x * m.x) % MOD; return *this; }
friend ModInt operator - (const ModInt& a) { ModInt res(a); if(res.x) res.x = MOD - res.x; return res; }
friend ModInt operator + (const ModInt& a, const ModInt& b) { return ModInt(a) += ModInt(b); }
friend ModInt operator - (const ModInt& a, const ModInt& b) { return ModInt(a) -= ModInt(b); }
friend ModInt operator * (const ModInt& a, const ModInt& b) { return ModInt(a) *= ModInt(b); }
static long long fp(long long u, long long k) {
long long res = 1LL;
while(k > 0LL) {
if(k & 1LL) res = (res * u) % MOD;
u = (u * u) % MOD;
k /= 2LL;
}
return res;
}
static constexpr int mod() {return MOD;}
ModInt fastpow(long long k) { return ModInt(fp(x, k)); }
ModInt inv() { return ModInt(fp(x, MOD-2)); }
ModInt& operator /= (const ModInt& m) { return *this *= ModInt(m).inv(); }
friend ModInt operator / (const ModInt& a, const ModInt& b) { return ModInt(a) *= ModInt(b).inv(); }
friend ostream& operator << (ostream& out, const ModInt& a) { return out << a.x; }
friend istream& operator >> (istream& in, ModInt& a) {return in >> a.x;}
};
const int MOD = 1e9 + 7;
using Mint = ModInt<MOD>;
int main(void)
{
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int nbLig, nbCol;
read(nbLig, nbCol);
vector<vector<Mint>> dp(nbLig+1, vector<Mint>(nbCol+1));
for (int col(0); col < nbCol; ++col)
dp[0][col] = 1;
for (ll ligRestante(1); ligRestante <= nbLig; ++ligRestante)
for (ll colRestante(0); colRestante <= nbCol; ++colRestante)
{
dp[ligRestante][colRestante] += dp[ligRestante-1][colRestante];
if (colRestante)
dp[ligRestante][colRestante] += 4*colRestante * dp[ligRestante-1][colRestante-1];
if (colRestante > 1)
dp[ligRestante][colRestante] += colRestante * (colRestante-1) / 2 * dp[ligRestante-1][colRestante-2];
if (ligRestante > 1 and colRestante > 0)
dp[ligRestante][colRestante] += colRestante * (ligRestante-1) * dp[ligRestante-2][colRestante-1];
}
writeln(dp[nbLig][nbCol]);
}
