#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  int c = 0;
  if (k == 0)
    cout << s << endl;
  else if (n == 1) {
    cout << "0" << endl;
  } else if (k >= 1 && n > 1) {
    int x = s[0] - '0';
    if (x > 1) {
      s[0] = '1';
      k--;
    }
    for (int i = 1; i < n && k > 0; i++) {
      x = s[i] - '0';
      if (x > 0) {
        s[i] = '0';
        k--;
      }
    }
    cout << s << endl;
  }
}
