#include <iostream>
#include <sstream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <string>
#include <cstring>
#include <bitset>
#include <functional>
#include <random>
#define REP(_i,_a,_n) for(int _i=_a;_i<=_n;++_i)
#define PER(_i,_a,_n) for(int _i=_n;_i>=_a;--_i)
#define hr putchar(10)
#define pb push_back
#define lc (o<<1)
#define rc (lc|1)
#define mid ((l+r)>>1)
#define ls lc,l,mid
#define rs rc,mid+1,r
#define x first
#define y second
#define io std::ios::sync_with_stdio(false)
#define endl '\n'
#define DB(_a) ({REP(_i,1,n) cout<<_a[_i]<<',';hr;})
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int P = 1e9+7, INF = 0x3f3f3f3f;
ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;}
ll qpow(ll a,ll n) {ll r=1%P;for (a%=P;n;a=a*a%P,n>>=1)if(n&1)r=r*a%P;return r;}
ll inv(ll x){return x<=1?1:inv(P%x)*(P-P/x)%P;}
inline int rd() {int x=0;char p=getchar();while(p<'0'||p>'9')p=getchar();while(p>='0'&&p<='9')x=x*10+p-'0',p=getchar();return x;}
//head



const int N = 5e3+10;
int n,m,f[N][N],g[N][N],pw[N],ipw[N];

int main() {
	pw[0] = ipw[0] = 1;
	REP(i,1,N-1) ipw[i]=inv(pw[i]=pw[i-1]*2ll%P);
	scanf("%d%d", &n, &m);
	REP(i,1,m) {
		f[1][i] = pw[i];
		g[1][i] = (g[1][i-1]+i)%P;
	}
	REP(i,2,n) REP(j,1,m) {
		f[i][j] = ((j+1ll)*f[i-1][j]+(ll)pw[j-1]*g[i-1][j-1])%P;
		g[i][j] = (g[i][j-1]+(ll)j*ipw[j]%P*f[i][j])%P;
	}
	printf("%d\n", f[n][m]);
}