#include <iostream>
using namespace std;

struct sum 
{
	int val;
	sum(int a) : val(a) {}
	
	sum operator()(int a) { return val + a; }
	
	operator int() { return val; }
};

sum f(int a)
{
	return a;
}

int main() {
	std::cout << f(1)(2)(3)(4) << std::endl;
}