#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector,fast-math")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma comment(linker, "/STACK:16777216")
using namespace std;
using matrix = vector<vector<long long>>;
void FAST_IO() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
const long long mod = 1e9 + 7;
const int MAXN = 5050;
long long dp[MAXN][MAXN];
long long binpow(long long a, long long n) {
  long long res = 1;
  while (n) {
    if (n & 1) {
      res = (res * a) % mod;
    }
    a = (a * a) % mod;
    n >>= 1;
  }
  return res;
}
signed main() {
  FAST_IO();
  int n, k;
  cin >> n >> k;
  dp[0][0] = 1;
  for (int i = 1; i < MAXN; ++i) {
    for (int j = 1; j <= i; ++j) {
      dp[i][j] = (dp[i - 1][j] * j + dp[i - 1][j - 1] * (n - j + 1)) % mod;
    }
  }
  long long ans = 0;
  for (int i = 1; i <= min(n, k); ++i) {
    ans = (ans + dp[k][i] * binpow(2, n - i)) % mod;
  }
  cout << ans;
}
