#include<bits/stdc++.h>
using namespace std;
#define int long long
const int MOD = 1e9+7;
int put(int a, int exp)
{
if(exp==0)
return 1;
if(exp%2==0)
return put((a*a)%MOD,exp/2);
else
return (put((a*a)%MOD,exp/2)*a)%MOD;
}
int cm[3005][3005];
int fact[6005];
int comb(int x, int y)
{
return cm[x][y];
}
int dp[3005][3005];
signed main()
{
fact[0]=1;
for(int i=1;i<=6000;i++)
fact[i]=(fact[i-1]*i)%MOD;
for(int i=0;i<=3000;i++)
{
for(int j=0;j<=i;j++)
{
if(i==j)
cm[i][j]=1;
else if(j==0)
cm[i][j]=1;
else
cm[i][j]=(cm[i-1][j-1]+cm[i-1][j])%MOD;
}
}
int n,m;
cin>>n>>m;
dp[n][m]=1;
for(int i=n;i>=0;i--)
{
for(int j=m;j>=0;j--)
{
if(i==n && j==m)
continue;
dp[i][j] += dp[i+1][j];
dp[i][j] += (dp[i+1][j+1] * (j+1) * 4LL)%MOD;
dp[i][j] += (dp[i+1][j+2] * comb(j+2,2))%MOD;
dp[i][j] += (dp[i+2][j+1] * (i+1) * (j+1))%MOD;
dp[i][j]%=MOD;
}
}
int sum=MOD-1;
for(int i=0;i<=m;i++)
sum=(sum+dp[0][i])%MOD;
cout<<sum;
return 0;
}
