輸入輸出

import java.io.*;
public class MSum
{
public static void main(String[] args)
{
 int i=1,m=1,n=0,sum1=1,sum2=0;
 /*System.out.print("輸入n:");//這是打印出來的一句話
        BufferedReader buff=new BufferedReader(new InputStreamReader(System.in));
        int n=buff.readLine(); */
 System.out.print("輸入n:");
 try{BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
 n=Integer.parseInt(br.readLine());
 }catch(IOException ex){}
 for(m=1;m<=n;m++)
 {
    for(i=m;i>0;i--)
    {
        sum1*=i;
    }
           sum2+=sum1;
 }
       System.out.println("Sum="+sum2);
}
}