#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false), cin.tie(0);
  int n, k, ct = 0;
  string s;
  cin >> n >> k >> s;
  if (n == 1) {
    if (k)
      cout << "0\n";
    else
      cout << s << '\n';
    return 0;
  }
  for (int i = 0; i < n; i++) {
    if (ct == k) break;
    if (!i) {
      if (s[i] != '1') s[i] = '1', ct++;
    } else {
      if (s[i] == '0') continue;
      s[i] = '0', ct++;
    }
  }
  cout << s << '\n';
  return 0;
}
