#include <bits/stdc++.h>
using namespace std;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
mt19937 rnf(2106);
const int N = 5003, M = 1000000007;
int n, k;
int dp[N][N];
int ast(int x, int n) {
  int ans = 1;
  while (n) {
    if (n % 2 == 1) ans = (ans * 1LL * x) % M;
    x = (x * 1LL * x) % M;
    n /= 2;
  }
  return ans;
}
void solv() {
  scanf("%d%d", &n, &k);
  dp[0][0] = 1;
  for (int i = 0; i <= min(n, k); ++i) {
    for (int j = 0; j <= k; ++j) {
      dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j] * 1LL * (n - i)) % M;
      dp[i][j + 1] = (dp[i][j + 1] + dp[i][j] * 1LL * i) % M;
    }
  }
  int ans = 0;
  for (int i = 1; i <= min(n, k); ++i) {
    ans = (ans + dp[i][k] * 1LL * ast(2, n - i)) % M;
  }
  printf("%d\n", ans);
}
int main() {
  solv();
  return 0;
}
