//*******************************************************************
// NOTE: please read the 'More Info' tab to the right for shortcuts.
//*******************************************************************
import java.util.*;

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

        while(true){
            System.out.println("wprowadz wart calkowita: ");
            if(scanner.hasNextInt()){
                int value = scanner.nextInt();
                if(value <= 100 && value >= 0){
                    System.out.println(value + " * 2 = " + value * 2);
                    break;
                }
                System.out.println("wartosc poza zakresem");
            } else {
                System.out.println("'" + scanner.next() + "' to nie jest wart. calkowita");
            }
        }
    }
}