#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <stack>
#include <algorithm>
using namespace std;
#define root 1,n,1
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define lr rt<<1
#define rr rt<<1|1
typedef long long LL;
typedef pair<int,int>pii;
#define X first
#define Y second
const int oo = 1e9+7;
const double PI = acos(-1.0);
const double eps = 1e-6 ;
const int N = 105 ;
const int mod = 1e9+7;

LL dp[N][N] , f[N] , C[N][N];
int n , m ;
void init() {
    f[0] = 1 ;
    for( int i = 1 ; i <= 50 ; ++i ) f[i] = f[i-1] * 2 ;
    for( int i = 0 ; i < N; ++i ){
        C[i][0] = C[i][i] = 1 ;
        for( int j = 1 ; j < i ; ++j ){
            C[i][j] = ( C[i-1][j] + C[i-1][j-1] ) % mod ;
        }
    }
}

void Run() {
    memset( dp , 0 , sizeof dp );
    dp[0][0] = 1 ;
    for( int i = 0 ; i < n ; ++i ){
        for( int j = 0 ; j <= m ; ++j ){
            for( int k = 0 ; j + k <= m ; k++ ){
                LL cnt = f[j]; if( !k ) cnt--; cnt %= mod ;
                dp[i+1][j+k] += ( dp[i][j] * cnt % mod * C[m-j][k] ) % mod;
                dp[i+1][j+k] %= mod ;
            }
        }
    }
    printf("%I64d\n",dp[n][m]);
}
int main()
{
    #ifdef LOCAL
        freopen("in.txt","r",stdin);
    #endif // LOCAL
    init();
    while( ~scanf("%d%d",&n,&m) ) Run();
}