#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main(void) {
  cin.tie(0)->sync_with_stdio(false);
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (s.size() == 1 && k > 0) {
    cout << 0 << '\n';
    return 0;
  }
  if (s[0] != '1' && k > 0) {
    s[0] = '1';
    k--;
  }
  int i = 1;
  while (k > 0 && i < s.size()) {
    if (s[i] != '0') {
      s[i] = '0';
      k--;
    }
    i++;
  }
  cout << s << '\n';
  return 0;
}
