#include<bits/stdc++.h>
using namespace std;
const int M=1000000007;
const int inv2=(M+1)/2;
int dp[5005][5005],inv[5005],p2[5005],s[5005],n,m;
void add(int &x,int y){x+=y;if (x>=M)x-=M;}

int solve(int x,int y){
	if (x==n) return 1;
	if (dp[x][y]!=-1) return dp[x][y];
	int ret=1ll*solve(x+1,y)*(y+1)%M;
	for (int k=2;k<=y;k++) add(ret,1ll*p2[k-2]*(y+1-k)%M*solve(x+1,y+1-k)%M);
	return dp[x][y]=ret;
}
int main(){
	cin >> n >> m;
	p2[0]=1; for (int i=1;i<=5000;i++) p2[i]=p2[i-1]*2%M;
	inv[0]=1; for (int i=1;i<=5000;i++) inv[i]=1ll*inv[i-1]*inv2%M;
	for (int i=1;i<=m;i++) dp[n][i]=1;
	for (int i=n-1;i>=0;i--){
        for (int j=1;j<=m;j++){
            s[j]=s[j-1];
            add(s[j],1ll*inv[j]*j%M*dp[i+1][j]%M);
        }
        for (int j=1;j<=m;j++){
            dp[i][j]=1ll*(j+1)*dp[i+1][j]%M;
            add(dp[i][j],1ll*p2[j-1]*s[j-1]%M);
        }
	}
	cout << dp[0][m] << endl;
}
