public static String[] getValidTwoDigits(String currencyCode) throws InterruptOperationException {
     writeMessage("Choose denomination and count format");
     String[] input;
     while (true) {
        input = readString().split(" ");
        int nominal;
        int total;
        try {
           nominal = Integer.parseInt(input[0]);
           total = Integer.parseInt(input[1]);
        } catch (Exception e) {
           writeMessage("Please specify valid data");
           continue;
        }
        if (nominal <= 0 || total <= 0) {
           writeMessage("Please specify valid data");
           continue;
        }
        break;
     }
     return input;
  }