Chapter 1: recursively find the factorial n of n!

long fac1(int n)
{
    
	long f;
	if (n == 1) f = 1;
	else f = n * fac1(n - 1);
	return (f);
}
int main()
{
    
	int n;
	long y;
	printf("  Please enter n（n < 13）：");
	scanf("%d", &n);
	if (n > 12)
	{
    
		printf("  Input n Over the limit 12, Please re-enter n.\n");
		return 0;
	}
	y = fac1(n);
	printf(" %d! = %ld\n", n, y);
	return 0;
}

result ：