#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k > 0) {
    if (s.length() != 1) {
      if (s[0] != '1') {
        s[0] = '1';
        k -= 1;
      }
    } else {
      s[0] = '0';
      k -= 1;
    }
  }
  int p = 1;
  while (p < n) {
    if (s[p] != '0' && k > 0) {
      s[p] = '0';
      k -= 1;
    }
    if (k == 0) break;
    p++;
  }
  cout << s;
  return 0;
}
