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