n!

import java.util.Scanner;
public class N
{public static void main(String[] args)
{
    int i,num=1;
    Scanner ab = new Scanner(System.in);
    System.out.println("请输入n:");
    int n=ab.nextInt();
    for(i=1;i<=n;i++)
        num=num*i;
    System.out.println("n!="+num);
}
}