Java 代码

import java.util.Scanner;

public class Main
{
    public static void main(String[] args)
    {
        Scanner cin = new Scanner(System.in);

        int num = cin.nextInt();

        int result = 1 ;
        int MOD = 1000000;

        for (int i = 1; i <= num; i++ )
        {
            result *= i;
            while (result % 10 == 0)
            {
                result = result/10 ;
            }
            result %= MOD;
        }

        System.out.println(result % 10);
    }
}