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