#include <bits/stdc++.h>
using namespace std;
const int md=1000000007;
int n,m,i,j;
long long f[5005][5005],s[5005][5005],pw2[5005],o[5005],k;
long long pw(long long a, int b) {
  if (b==0) return 1LL;
  if (b&1) return (pw(a,b-1)*a)%md;
  long long x=pw(a,b/2);
  return (x*x)%md;
}
int main() {
  scanf("%d%d",&m,&n);
  for (pw2[0]=o[0]=i=1; i<=n; i++) {
    f[0][i]=1;
    pw2[i]=(pw2[i-1]*2)%md;
    o[i]=pw(pw2[i],md-2);
  }
  for (i=1; i<=m; i++) {
    for (k=1; k<=n; k++) s[i-1][k]=(s[i-1][k-1]+((f[i-1][k]*k)%md)*o[k+1])%md;
    for (j=1; j<=n; j++) {
      f[i][j]=(f[i-1][j]*(j+1LL))%md;
      f[i][j]=(f[i][j]+s[i-1][j-1]*pw2[j])%md;
    //f[i][j]=(f[i][j]+s[i-1][j-1]*pw2[j])%md;
    //s[i][j]=(s[i][j-1]+((f[i][j]*j)%md)*o[j+1])%md;
    //s[i][j]=(((f[i][j]*j)%md)*o[j+1])%md;
    //printf("%d %d = %d\n",i,j,f[i][j]);
    }
  }
  printf("%d\n",f[m][n]);
  return 0;
}