#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k;
  string s;
  cin >> n >> k >> s;
  if (k == 0) {
    cout << s << endl;
    return 0;
  }
  if (n == 1) {
    cout << 0 << endl;
    return 0;
  }
  if (s[0] == '1') k++;
  s[0] = '1';
  for (int i = 1; i < k; ++i) {
    if (k > n) k = n;
    if (s[i] == '0')
      k++;
    else
      s[i] = '0';
  }
  cout << s << endl;
}
