check if username or password is too long
// If username is too long
  fgets(user_id, MAXLINE, stdin);
  if(strlen(user_id) > MAX_PASSWORD + 1) {
      printf(NO_USER);
      exit(1);
  }

  // If password is too long
  fgets(password, MAXLINE, stdin);
  if(strlen(password) > MAX_PASSWORD + 1) {
      printf(NO_USER);
      exit(1);
  }
