#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#define llint long long
#define inf 1e18
#define rep(x, s, t) for(llint (x) = (s); (x) < (t); (x)++)
#define Rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define mod 1000000007

using namespace std;
typedef pair<llint, llint> P;

llint n, m;
llint dp[5005][5005];
llint beki[5005], beki2[5005], sum[5005];

int main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> m;
	
	beki[0] = 1, beki2[0] = 1;
	for(int i = 1; i < 5005; i++) beki[i] = beki[i-1] * 2, beki[i] %= mod;
	for(int i = 1; i < 5005; i++) beki2[i] = beki2[i-1] * ((mod+1)/2) % mod, beki2[i] %= mod;
	
	dp[0][m] = 1;
	for(int i = 1; i <= n; i++){
		for(int j = 2; j <= m; j++) sum[j] = sum[j-1] + dp[i-1][j]*beki[j]%mod, sum[j] %= mod;
		for(int j = 1; j <= m; j++){
			dp[i][j] = dp[i-1][j]*(j+1)%mod;
			dp[i][j] += (sum[m] - sum[j] + mod) % mod * j % mod * beki2[j+1] % mod, dp[i][j] %= mod;
		}
	}
	
	llint ans = 0;
	for(int i = 1; i <= m; i++) ans += dp[n][i], ans %= mod;
	cout << ans << endl;
	
	return 0;
}