Recursive lambda calculating Fibonacci number in C++

main.cpp

#include <iostream>
#include <cstdlib>

int main( int argc, char* argv[]) { 
    typedef unsigned long long int num_type;
    std::cout << [](auto lambda, num_type number) -> num_type { return lambda(lambda, number); } ([](auto lambda, num_type number) -> num_type { return number <= 2 ? num_type(1) : lambda(lambda, number-1) + lambda(lambda, number-2); }, std::atoi(argv[1])) << std::endl;
    return EXIT_SUCCESS;
}