#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n, k;
  cin >> n >> k;
  string s, s1;
  cin >> s;
  if (k == 0) {
    cout << s;
  } else if (n == 1) {
    cout << 0 << "\n";
  } else {
    if (s[0] != '1') {
      k--;
    }
    s1.push_back('1');
    int i = 1;
    while (k && i < n) {
      if (s[i] != '0') k--;
      s1.push_back('0');
      i++;
    }
    for (; i < n; i++) {
      s1.push_back(s[i]);
    }
    cout << s1 << "\n";
  }
  return 0;
}
