#include <iostream>
#include <string>
template <class T1, class T2>
class Pair {
 private:
     T1 a;
     T2 b;
 public:
     T1 & first();
     T2 & second();
     T1 first() const { return a; }
     T2 second() const { return b; }
     Pair(const T1 & aval, const T2 & bval) : a(aval), b(bval) { }
     Pair() {}
};
template<class T1, class T2>
T1 & Pair<T1,T2>::first() { return a; }

template<class T1, class T2>
T2 & Pair<T1,T2>::second() { return b; }

Pair myPair(5,10);
cout << myPair.first();