#include <iostream>
#include <vector>
#include <queue>
using namespace std;
#define ll long long
const int N=302,mod=1e9+7;
ll dp[N][N],ndp[N][N];
int main()
{
int n,m;
cin>>n>>m;
dp[m][0]=1;
// ndp[m][0]=1;
for(int i=1;i<=n;i++)
{
for(int j=0;j<=m;j++)
{
for(int k=0;k<=m;k++)
{
// leave row empty
ndp[j][k]+=dp[j][k];
ndp[j][k]%=mod;
// dp[j][k]*3*j --> dp[j-1][k] // face up left right
if(j>0)
{
ndp[j-1][k]+=(dp[j][k]*3*j)%mod;
ndp[j-1][k]%=mod;
}
// dp[j][k]*j --> dp[j-1][k+1] // make it face down
if(j>0)
{
ndp[j-1][k+1]+=(dp[j][k]*j)%mod;
ndp[j-1][k+1]%=mod;
}
// dp[j][k]*(jC2) --> dp[j-2][k] // make them face each other
if(j>1)
{
ll w=((j*(j-1))/2)%mod;
ndp[j-2][k]+=(dp[j][k]*w)%mod;
ndp[j-2][k]%=mod;
}
// dp[j][k]*k --> dp[j][k-1] // Pair one of the previous facing down by making this one facing up
if(k>0)
{
ndp[j][k-1]+=(dp[j][k]*k)%mod;
ndp[j][k-1]%=mod;
}
}
}
for(int j=0;j<=m;j++)
{
for(int k=0;k<=m;k++)
{
dp[j][k]=ndp[j][k];
ndp[j][k]=0;
}
}
}
// summation dp
ll ans=0;
for(int j=0;j<=m;j++)
{
for(int k=0;k<=m;k++)
{
ans+=dp[j][k];
ans%=mod;
}
}
ans=(ans+mod-1)%mod;
cout<<ans<<endl;
}
