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