#define led1 2
#define led2 3
#define led3 4
const float BETA = 3950; 

void setup() {
Serial.begin(9600);
}

void loop() {
 int analogValue = analogRead(A1);
 float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;

 if(10 <= celsius && celsius <= 15)
  {
    
    Serial.print("Normal temperature  ");
    Serial.print(celsius);
    Serial.println(" ℃");
    digitalWrite(led1, HIGH);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
  } 
    else if (15 < celsius && celsius <= 20)
    {
       Serial.print("Warning! The temperature is above normal!  ");
    Serial.print(celsius);
    Serial.println(" ℃");
    digitalWrite(led1, LOW);
    digitalWrite(led2, HIGH);
    digitalWrite(led3, LOW);
    }

       else if (celsius > 20)
    {
       Serial.print("Danger! Elevated temperature!  ");
    Serial.print(celsius);
    Serial.println(" ℃");
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, HIGH);
    } 
    else 
    {
       Serial.println("Temperature is below normal!  ");
    Serial.print(celsius);
    Serial.println(" ℃");
    digitalWrite(led1, LOW);
    digitalWrite(led2, LOW);
    digitalWrite(led3, LOW);
  }

  delay(3000);
}