// Repeatedly prompts the user for numbers until
// a non-negative number is entered.

import java.util.*;

public class Negatives {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        
        System.out.print("Type a non-negative integer: ");
        int n = console.nextInt();
        
        while (n < 0) {
            System.out.print("Invalid number, try again: ");
            n = console.nextInt();
        }
        
        System.out.println(n + " squared is " + n*n);
    }
}