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