#include <bits/stdc++.h>

#define F first
#define S second
#define pb push_back
#define all(x) x.begin(), x.end()
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int N = 5000 + 10;
const int MOD = 1000000007;
const int LOG = 20;
const int INF = 1000000010;
const int delta = 11353;

int n, m, DP[N][N], T2[N];

inline int mul(int a, int b){
	return a * 1ll * b % MOD;
}

inline int add(int a, int b){
	a += b;
	if (a >= MOD)a -= MOD;
	return a;
}

int32_t main(){
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	cin >> n >> m;
	T2[0] = 1;
	for (int i = 1; i < N; i++) T2[i] = T2[i - 1] * 2ll % MOD;
	for (int i = 1; i <= m; i++) DP[1][i] = T2[i];
	for (int i = 2; i <= n; i++){
		int sm = 0;
		for (int j = 1; j <= m; j++){
			DP[i][j] = mul(DP[i - 1][j], j + 1);
			if (j > 1){
				sm = mul(sm, 2);
				sm = add(sm, mul(j - 1, DP[i - 1][j - 1]));
				DP[i][j] = add(DP[i][j], sm);
			}
//			cout << i << ' ' << j << ' ' << DP[i][j] << '\n';
		}
	}
	cout << DP[n][m];
	return 0;
}
