public boolean less20(int n) {
  if (n % 20 == 18) {
    return true;
  }
  else if (n %20 == 19) {
    return true;
  }
  else {
    return false;
  }
}

public boolean less20(int n) {
  if (n % 20 == 18 || n %20 == 19) {
    return true;
  }
  else {
    return false;
  }
}

public boolean less20(int n) {
  return n % 20 == 18 || n %20 == 19;
}

public boolean less20(int n) {
  int rem = n % 20;
  return rem == 18 || rem == 19;
}

public boolean less20(int n) {
  int rem = n % 20;
  return 18 <= rem && rem <= 19;
}