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