/**
____ ____ ____ __________________ ____ ____ ____
||I || ||c || ||e || || || ||M || ||a || ||n ||
||__|| ||__|| ||__|| ||________________|| ||__|| ||__|| ||__||
|/__\| |/__\| |/__\| |/________________\| |/__\| |/__\| |/__\|
*/
#include <iostream>
#include <chrono>
//#include <vector>
#define maxn 3005
#define maxlog 20
#define INF 1000000010
#define mod 1000000007
#define LINF 1000000000000000005
#define endl '\n'
#define pb(x) push_back(x)
#define X first
#define Y second
#define control cerr<<"passed"<<endl;
///#pragma GCC optimize("O3" , "Ofast" , "unroll-loops" , "fast-math")
///#pragma GCC target("avx2")
using namespace std;
std::chrono::high_resolution_clock::time_point startT, currT;
constexpr double TIME_MULT = 1;
double timePassed()
{
using namespace std::chrono;
currT = high_resolution_clock::now();
double time = duration_cast<duration<double>>(currT - startT).count();
return time * TIME_MULT;
}
long long dp[maxn][maxn];
int n, m;
void read()
{
cin >> n >> m;
}
void calc_dp()
{
for(int i = 0; i <= max(n , m); i++)
{
dp[i][0] = 1;
dp[0][i] = 1;
}
for(int i = 1; i <= n; i++)
for(int j = 1; j <= m; j++)
{
dp[i][j] += dp[i - 1][j];
dp[i][j] += dp[i - 1][j - 1] * j * 4LL;
if(j > 1)
dp[i][j] += dp[i - 1][j - 2] * (j - 1) * j / 2LL;
if(i > 1)
dp[i][j] += j * (i - 1) * dp[i - 2][j - 1];
dp[i][j] %= mod;
}
cout << (dp[n][m] + mod - 1) % mod << endl;
}
int main()
{
/**#ifdef ONLINE_JUDGE /// promeni
freopen("taxi.in", "r", stdin);
freopen("taxi.out", "w", stdout);
#endif*/
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//startT = std::chrono::high_resolution_clock::now();
read();
calc_dp();
return 0;
}
