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