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