Life,Universe and Everything

Please tell me why this shows runtime error.......

import java.util.ArrayList;
import java.util.Scanner;

class Life_Universe_And_Everything {

    ArrayList<Integer> list=new ArrayList<Integer>();
    Scanner sc=new Scanner(System.in);
    public  void input()
    {
        int val;
        while(true)
        {
            val=sc.nextInt();
            if(val==-1)
                break;
            if(val>=0 && val<=99)
                list.add(val);
        }
    }
    public void display()
    {
            for(Integer a:list)
            {
                if(a==42)
                    break;
                System.out.println(a);
            }
    }
    public static void main(String[] args) {

        Life_Universe_And_Everything lue=new Life_Universe_And_Everything();
        lue.input();
        lue.display();
    }
}