#include <iostream>
#include <functional>

using namespace std;

template<class T>
struct lazy
{
    lazy() = default;
    using ntype = function<T()> ;
    ntype number;

    lazy(T num) {
        number = [=] ( ) -> T {
           return num;
        };
    }

    lazy operator +(lazy one){
        lazy result;
        result.number = [=] () -> T {
            return one.number() + number();
        };
        return result;
    }

    operator T(){
        return number ();
    }
};

using lazy_int = lazy<int>;
int main(int argc, char *argv[])
{
    lazy_int a = 7;
    lazy_int b = 3;
    cout << a + b << endl;
    a = a + b;
    cout << a << endl;
}