用java写随机出题

 import java.io.*;      //输入函数包
 public class hello{
     public static void main(String args[]){
         String s="";
         int sum1,sum2,sum3;
         sum1=(int)(Math.random()*100+1);
         sum2=(int)(Math.random()*100+1);
         sum3=(int)(Math.random()*100+1);
         System.out.println(sum1+"+"+sum2+"-"+sum3);
         try
         {
             BufferedReader in=new BufferedReader(
                                                 new InputStreamReader(System.in));
             s=in.readLine();
         }
         catch(IOException e){}
         int sum=Integer.parseInt(s);
         if(sum==sum1+sum2-sum3)
             System.out.println("yes");
         else
             System.out.println("NO");
     }
 }