#include <stdio.h>

long long int f (long long int n);

int main(void)
{
   printf("f(n) = %lld\n", f(5));

   return 0;
}

long long int f (long long int n) 
{
   if ((n == 1) || (n == 0))
      return 1;
   else
      return (f(n-1) + f(n-2));

}