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