> I only add the two sentence as I marked,Then I get a runtime error.Help me,Thank you.
> import java.io.*;
> import java.util.*;
> public class Main
> {
>             public static void main(String args[]) throws Exception
>             {
>             	    Scanner cin=new Scanner(System.in);
>                     for(;;)//here
>                     {
>                     	if(cin==null) break;//here
>                     	int a=cin.nextInt();
>                     	int b=cin.nextInt();
>                         System.out.println(a+b);	
>                     }
>             }
> }