#include <string.h>
#include <iostream>
#include <unordered_set>

using namespace std;

struct eqstr
{
  bool operator()(const char* s1, const char* s2) const
  {
    return strcmp(s1, s2) == 0;
  }
};

void lookup(const unordered_set<const char*, hash<const char*>, eqstr>& Set,
            const char* word)
{
  unordered_set<const char*, hash<const char*>, eqstr>::const_iterator it
    = Set.find(word);
  cout << word << ": "
       << (it != Set.end() ? "present" : "not present")
       << endl;
}

int main()
{
  unordered_set<const char*, hash<const char*>, eqstr> Set;
  Set.insert("kiwi");
  Set.insert("plum");
  Set.insert("apple");
  Set.insert("mango");
  Set.insert("apricot");
  Set.insert("banana");

  lookup(Set, "mango");
  lookup(Set, "apple");
  lookup(Set, "durian");
}