HW4.2

 import java.util.Scanner;

 public class Solution
 {
     public static void main(String[] args)
     {
         Scanner input = new Scanner(System.in);
         int correctCount = 0;
         int answer = 0;
         int number1;
         int number2;

         long startTime = System.currentTimeMillis();

         for(int i = 0; i < 10; i++)
         {
             number1 = (int)(Math.random() * 15);
             number2 = (int)(Math.random() * 15);
             System.out.print(number1 + " + " + number2 + " = ? ");
             answer = input.nextInt();
             if(answer == number1 + number2)
                 correctCount++;
         }

         input.close();

         long endTime = System.currentTimeMillis();
         long usedTime = (endTime - startTime) / 1000;

         System.out.println("You have " + correctCount + " answers");
         System.out.println("Used time: " + usedTime);
     }
 }