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