Данный код проходит валидатор. Почему уже после вывода на экран требуется еще один ввод? Поток же потом закрывается, или? 
public class Solution {
    public static volatile AtomicInteger countReadStrings = new AtomicInteger(0);
    public static volatile BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws IOException {
        //read count of strings
        int count = Integer.parseInt(reader.readLine());

        //init threads
        ReaderThread consolReader1 = new ReaderThread();
        ReaderThread consolReader2 = new ReaderThread();
        ReaderThread consolReader3 = new ReaderThread();

        consolReader1.start();
        consolReader2.start();
        consolReader3.start();

        while (count > countReadStrings.get()) {
        }

        consolReader1.interrupt();
        consolReader2.interrupt();
        consolReader3.interrupt();

        System.out.println("#1:" + consolReader1);
        System.out.println("#2:" + consolReader2);
        System.out.println("#3:" + consolReader3);

        reader.close();
    }

    public static class ReaderThread extends Thread {
        private List<String> result = new ArrayList<String>();

        public void run() {
            try {
                while(!(Thread.currentThread().isInterrupted())){
                    if(reader.ready()) {
                result.add(reader.readLine());
                countReadStrings.incrementAndGet();
                    }
                }
            } catch (IOException ex) {

            }
        }

        @Override
        public String toString() {
            return result.toString();
        }
    }
}