#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  string str;
  cin >> n >> k >> str;
  if (k == 0) {
    cout << str << endl;
    return 0;
  }
  if (str.size() == 1) {
    str = "0";
    cout << str << endl;
    return 0;
  }
  if (str[0] != '1') {
    str[0] = '1';
    k -= 1;
  }
  for (int i = 1, j = 1; j <= k && i < n; i++) {
    if (str[i] != '0') {
      str[i] = '0';
      j++;
    }
  }
  cout << str << endl;
  return 0;
}
