void setup() {
  Serial.begin(9600);
}
void loop() {
  for (int suhu = 0; suhu <= 30; suhu++){
    Serial.println(suhu);
    delay(500);
  }
  for (int suhu = 30; suhu >= 0; suhu--){ 
    Serial.println(suhu); 
    delay(500);
  }
}