class Factor {
	static long factorial(long n) {
		if(n==1)
			return 1;
		else
			return n*factorial(n-1);
	}
	public void show() {
		System.out.println("計算完畢");
	}
}
class ComputeFactor {
	public static void main(String args[]) 
	{
		long n=5;
		long result=Factor.factorial(n);
		System.out.println(n+"!= "+result);
		Factor A=new Factor();
		A.show();
	}
}