#include <bits/stdc++.h>
using namespace std;
const double PI = 3.141592654;
void solve() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (s[0] != '1' && k && s.size() != 1) {
    s[0] = '1';
    k--;
  }
  for (int i = 1, m = 0; (i < s.size() && m < k); i++) {
    if (s[i] != '0') {
      s[i] = '0';
      m++;
    }
  }
  if (s.size() == 1 && k) s[0] = '0';
  cout << s << "\n";
}
int main() {
  cin.tie(0), cout.tie(0), cin.sync_with_stdio(0), cout.sync_with_stdio(0);
  solve();
  return 0;
}
