#include <iostream>
#include <cstdio>
using namespace std;
const int N=305;
const int mod=1e9+7;
typedef long long ll;
int n,m;
ll f[N][N][N];
int main(){
	freopen("rotk.in","r",stdin);
	freopen("rotk.out","w",stdout);
	cin>>n>>m;
	f[0][0][1]=1;
	for(int i=0;i<m;i++){
		for(int j=0;j<=n;j++){
			for(int k=0;k<=n-j;k++){
				if(!f[i][j][k])continue;
				f[i+1][j+1][k]+=f[i][j][k]*(n-j-k)%mod;
				f[i+1][j+1][k]%=mod;
				f[i+1][j][k]+=f[i][j][k]*j%mod;
				f[i+1][j][k]%=mod;
				f[i+1][0][j+k]+=f[i][j][k]*k%mod;
				f[i+1][0][j+k]%=mod;
			}
		}
	}
	cout<<f[m][0][n]<<endl;
	return 0;
}