#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int n, k, ans, s[5005][5005];
inline int read() {
  int num = 0;
  char cc = getchar();
  while (cc < 48 || cc > 57) cc = getchar();
  while (cc > 47 && cc < 58)
    num = (num << 1) + (num << 3) + (cc ^ 48), cc = getchar();
  return num;
}
inline int power(int a, int b) {
  int res = 1;
  while (b) {
    if (b & 1) res = 1ll * res * a % mod;
    a = 1ll * a * a % mod;
    b >>= 1;
  }
  return res;
}
int main() {
  n = read(), k = read();
  s[0][0] = 1;
  for (int i = 1; i <= k; i++)
    for (int j = 1; j <= i; j++)
      s[i][j] = (s[i - 1][j - 1] + 1ll * s[i - 1][j] * j) % mod;
  int fac = 1, mul2 = power(2, n), inv = power(2, mod - 2);
  for (int i = 0; i <= k; i++) {
    (ans += 1ll * s[k][i] * fac % mod * mul2 % mod) %= mod;
    fac = 1ll * fac * (n - i) % mod;
    mul2 = 1ll * mul2 * inv % mod;
  }
  if (!k) ans--;
  printf("%d", ans);
}
