[백준] 10872번 : 팩토리얼 - C#

https://www.acmicpc.net/problem/10872

using System;

class Program
{
    static void Main(string[] args) {
        string s=Console.ReadLine();
        int a=int.Parse(s);
        int num=1;
        if(a==0) Console.Write(1);
        else{
            for(int i=1;i<=a;i++){
                num=num*i;
            }
            Console.Write(num);
        }
    }
}