#define DEBUG(...) cerr << __VA_ARGS__ << endl;

#ifndef CDEBUG
#undef DEBUG
#define DEBUG(...) ((void)0);
#define NDEBUG
#endif

#define ran(i, a, b) for (auto i = (a); i < (b); i++)

#include <bits/stdc++.h>
typedef long long ll;
typedef long double ld;
using namespace std;
const int mod = 1e9 + 7;
#ifndef M_PI
const double M_PI = acos(-1.0);
#endif

const int nmax = 5005;
const ll two_inv = (mod+1)/2;

ll two_pow[nmax];
ll l_mult[nmax];
ll arr[nmax];
ll tmp[nmax];

int main() {
  two_pow[0] = 1;
  l_mult[0] = 1;
  ll two_inv_pow = (mod+1)/2;
  for(int i=1; i<nmax; ++i){
    two_pow[i] = two_pow[i-1]*2%mod;
    l_mult[i] = (i+1)*two_inv_pow%mod;
    two_inv_pow *= two_inv;
    two_inv_pow %= mod;
  }
  int n, m;
  cin>>n>>m;
  arr[m-1]=1;
  for(int i=0; i<n; ++i){
    ll par = 0;
    for(int j=m-1; j>=0; --j){
      tmp[j] = (par*l_mult[j] + arr[j]*(j+2))%mod;
      if(j){
        par += arr[j]*two_pow[j-1];
        par %= mod;
      }
    }
    swap(tmp, arr);
  }
  ll res = 0;
  for(int j=m-1; j>=0; --j){
    res += arr[j];
  }
  res %= mod;
  cout<<res<<endl;
  return 0;
}
