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