#include <stdio.h>
#include <stdlib.h>

int
fibofnc (int n)
{
    if (n <= 0)
        return 0;
    if (n == 1)
        return 1;
    return fibofnc (n - 1) + fibofnc (n - 2);
}

int
main (int argc, char *argv[])
{
    int n;
    int res;
    char *p;

    if (argc >= 2) {
        n = strtol (argv[1], &p, 0);
        if ((p == argv[1]) || *p) {
            fprintf (stderr, "The \"%s\" string is not a number\n", argv[1]);
            return 1;
        }
    } else {
        printf ("Input number: ");
        scanf ("%d", &n);
    }

    res = fibofnc (n);

    printf ("fibofnc(%d)=%d\n", n, res);

    return 0;
}