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