public static int getTotalUsers() {
    String userName;
    long keyDate;
    int userNumber = 0;
    do {
      userName = null;
      keyDate = 0;
      userName = SafeSlingerPrefs.getContactName(userNumber);
      keyDate = SafeSlingerPrefs.getKeyDate(userNumber);
      if (!TextUtils.isEmpty(userName)) {
        userNumber++;
      }
    } while (keyDate > 0);

    // always at least 1
    return userNumber > 1 ? userNumber : 1;
  }