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