A simple Random Algorithm with Square Method

import java.util.Scanner;

/**
 *
 * @author Hantack
 */
public class Simulation {

    public int createTail(int n) {

        n *= n; String ns = String.valueOf(n);
        ns = (!(ns.length() % 2 == 0)) ? "0" + ns : ns;
        ns = ns.substring(((ns.length() / 2) - 2), ((ns.length() / 2) + 2));
        System.out.println(ns);
        return Integer.parseInt(ns);
    }

    String input = "";

    public static void main(String[] args) {
        Simulation sim = new Simulation();
        Scanner xr = new Scanner(System.in);
        sim.input = xr.nextLine();
        try {
            int n = Integer.parseInt(sim.input);
            if (n > 999) {
            for (int i = 0; i < 5; i++) {
                n = sim.createTail(n);
            }

        } else {
            System.out.println("Give a valid tail");
        }
        }catch(java.lang.NumberFormatException err){
            System.out.println("Give a value in the range of Integer");
        }


    }

}