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