const float BETA = 3950; 
int analogValue;
float celsius;

void setup() {
  Serial.begin(9600);
  pinMode (A0, INPUT);
  pinMode (9, INPUT);
  pinMode (13, OUTPUT);
  pinMode (12, OUTPUT);
  pinMode (11, OUTPUT);
  pinMode (10, OUTPUT);
}

void loop() {
  analogValue = analogRead(A0);
  celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
  Serial.print("TEMPERATURE: ");
  Serial.print(celsius);
  Serial.println(" °C");

  digitalWrite(9, LOW);
  digitalWrite(10, LOW);
  digitalWrite(11, LOW);
  digitalWrite(12, LOW);
  digitalWrite(13, LOW);

   if(celsius >= -24 && celsius <= 0){
    digitalWrite(9, HIGH);
  }
  
  if(celsius >= 1 && celsius <= 20){
    digitalWrite(9, HIGH);
    digitalWrite(10, HIGH);
    
  }
 
  if(celsius >= 21 && celsius <= 40){
    digitalWrite(9, HIGH);
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
  }
  
  if(celsius >= 41 && celsius <= 60){
    digitalWrite(9, HIGH);
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(12, HIGH);
  }
  
  if(celsius >= 61 && celsius <= 80){
    digitalWrite(9, HIGH);
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(12, HIGH);
    digitalWrite(13, HIGH);
  }
  
  
}