Implementing an Abstract Class

import java.util.Scanner;
abstract class A{
    public abstract void special(int n);
}
class B extends A{
    public void special(int n){
        int i, j;
        for(i = 1000; i<=n; i++)
            for(j = 1; j<i/2; j++)
                if(j*j == i){
                    System.out.println(i+" is a perfect square.");
                    break;
                }
    }
}
class Squarenos{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = 0;
        while(n>1000 && n<9999){
            System.out.println("Enter the a number in between 1000 and 9999: ");
            n = sc.nextInt();
        }
        new B().special(n);
    }
}