/*
CSE 142, Autumn 2007, Marty Stepp

Expected output:
Type a non-negative integer: -5
Invalid number, try again: -1
Invalid number, try again: -235
Invalid number, try again: -87
Invalid number, try again: 11
11 squared is 121
*/

import java.util.*;   // for Scanner

public class NonNegativeInput {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);

        // read the first number
        System.out.print("Type a non-negative integer: ");
        int number = console.nextInt();
        
        // read additional numbers, if necessary
        while (number < 0) {
            System.out.print("Invalid number, try again: ");
            number = console.nextInt();
        }
        
        // report results
        System.out.println(number + " squared is " + (number * number));
    }
}