#include <queue> // priority_queue
#include <string>

class Destination {
 unsigned int distance;  string destination;
 friend ostream& operator<<(ostream &, const Destination &) ;
public:

 Destination (const string dt, unsigned int ds)
 : distance(ds), destination(dt) {}
 
 bool operator< (const Destination & right) const {
  return distance < right.distance; 
 }
};
ostream & operator << (ostream& os, const Destination & p) {
 return os << p.destination << " " << p.distance ;
}
int main() {
  // keep a priority queue of distances to cities
   priority_queue < Destination > que;
   que.push(Destination("halifax",   0));
   que.push(Destination("truro",   100));
   que.push(Destination("moncton", 230));

   while (! que.empty() ) { // remove top entry from queue
      cout << que.top() << endl;
      que.pop();
   }
}
/* output
moncton 230
truro 100
halifax 0
*/