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