POJ 2807:两倍

import java.util.Scanner;

public class Main {

    private static int[] getNumbers(String[] strings) {
        int[] numbers = new int[strings.length];
        
        for (int i = 0; i < strings.length; i++) {
            numbers[i] = Integer.parseInt(strings[i]);
        }
        
        return numbers;
    }
    
    private static boolean isDouble(int n1, int n2) {
        if (n1 == 0 || n2 == 0) {
            return false;
        }
        if ((n1 * 2 == n2) || (n2 * 2 == n1)) {
            return true;
        }
        return false;
    }
    
    private static int getDoubleCounts(int[] ns) {
        int count = 0;
        for (int i = 0; i < ns.length; i++) {
            for (int j = i + 1; j < ns.length; j++) {
                if (isDouble(ns[i], ns[j])) {
                    count++;
                }
            }
        }
        return count;
    }
    
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        while (true) {
            String s = input.nextLine();
            if (s.equals("-1")) {
                break;
            }
            String[] numStrings = s.split(" ");
            int[] number = getNumbers(numStrings);
            System.out.println(getDoubleCounts(number));
        }
    }

}