#include <iostream>
#include <vector>
using namespace std;

template <typename T, typename Comparator>
const T & findMax(const vector<T> & a, Comparator isLessThan) {
   int maxIndex = 0;
   
   for (int i = 1; i < a.size(); i++) {
      if (isLessThan( a[maxIndex], a[i] )) {
         maxIndex = i;
      }
   }
   return a[maxIndex];
}

class LessThanByLength {
public:
  bool operator() ( const string & lhs, const string & rhs) const {
    return lhs.size() < rhs.size(); 
  }
};

int main() {
  vector<string> a;
  a.push_back("abc");
  a.push_back("aceg");
  a.push_back("xz");

  cout << findMax(a, LessThanByLength() ) << endl;
  return 0;
}