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