#include<fstream>
#include<utility>
#include<iostream>
constexpr int fibonacci(const int value) {
	if (value < 2) { return value; }
	auto n2 = 0;
	auto fib = 1;
	for (int pos = 2; pos <= value; ++pos) {
		n2 = std::exchange(fib, fib + n2);
	}
	return fib;
}
auto main() ->int {
	int number;
	std::cout << fibonacci(10);
	std::ifstream input("kfib.txt");
	input >> number;
	std::ofstream output("kfib.out");
	output << fibonacci(10);


}