#include <stdio.h>
long fun(int  g)
{
	switch(g)
	{
	case 0:
		return 0;
	case 1:
		return 0;
	case 2:
		return 1;
	}
	return (fun(g-1) + fun(g-2));
}
main()
{
	long  fib;
	int  n;
	printf("Input n:  ");
	scanf("%d", &n);
	printf("n=%d\n", n);
	fib = fun(n);
	printf("fib = %d\n\n", fib);
}