#include <stdio.h>

int fib_worker(int a, int b, int n)
{
    if (n == 0) return a;

    return fib_worker(b, a+b, n - 1);
}

int fibonacci(int n)
{
    return fib_worker(0, 1, n);
}

int main()
{
  printf("%d\n", fibonacci(45));
  return 0;
}