#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int mod=1e9+7;
const int inv2=(mod+1)/2;
#define N 5005
inline int read(){
	int x=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-')f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		x=(x<<1)+(x<<3)+c-'0';
		c=getchar();
	}
	return x*f;
}
int dp[N][N],n,m;
int pw[N],inv[N],s[N];
int main(){
	n=read(),m=read();
	pw[0]=inv[0]=1;
	for(int i=1;i<=m;++i){
		pw[i]=(pw[i-1]<<1)%mod;
		inv[i]=1LL*inv[i-1]*inv2%mod;
	}
	for(int i=1;i<=m;++i){
		dp[1][i]=pw[i];
		s[i]=(s[i-1]+1LL*dp[1][i]*i%mod*inv[i+1])%mod;
	}
	for(int i=2;i<=n;++i){
		for(int j=1;j<=m;++j){
			dp[i][j]=(1LL*dp[i-1][j]*(j+1)+1LL*s[j-1]*pw[j])%mod;
		}
		for(int j=1;j<=m;++j){
			s[j]=(s[j-1]+1LL*dp[i][j]*j%mod*inv[j+1])%mod;
		}
	}
	printf("%d\n",dp[n][m]);
	return 0;
}
