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