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