#include <iostream>
#include <iomanip>
#include <chrono>

using namespace std;
using namespace std::chrono;

/**
 * Calculate the nth fibonacci recursively.
 * (Generally a very bad idea.)
 * @param n which fibonacci number to calculate.
 */
long fibonacci(int n);

const int N1 = 46;
const int N2 = 45;

int main()
{
    cout << "Calculating fibonacci(" << N1 << ") ... ";  cout.flush();
    auto   start1   = steady_clock::now();
    long   result1  = fibonacci(N1);
    auto   end1     = steady_clock::now();
    double elapsed1 = duration_cast<milliseconds>(end1 - start1).count();

    cout << result1 << endl;
    cout << "Elapsed time = " << elapsed1/1000  << " seconds" << endl;

    cout << endl;
    cout << "Calculating fibonacci(" << N2 << ") ... ";  cout.flush();
    auto   start2   = steady_clock::now();
    long   result2  = fibonacci(N2);
    auto   end2     = steady_clock::now();
    double elapsed2 = duration_cast<milliseconds>(end2 - start2).count();

    cout << result2 << endl;
    cout << "Elapsed time = " << elapsed2/1000 << " seconds" << endl;

    cout << endl;
    double total_elapsed = duration_cast<milliseconds>(end2 - start1).count();
    cout << "Total elapsed time = " << total_elapsed/1000 << " seconds" << endl;

    return 0;
}

long fibonacci(int n)
{                                                    
    if (n <= 1) return n;
    else        return fibonacci(n-2) + fibonacci(n-1);
}