int ledPin=13;
int sensorPin=A0;
int temp=0;

void setup() {
  // put your setup code here, to run once:
pinMode (ledPin, OUTPUT);
}

void loop() {
  // read the value on sensorPin
  int sensorPin = analogRead(A0);
  temp = (5.0 * sensorPin * 100.0) / 1024;  //formula to convert voltage into Celsius degrees
  
  if(temp>=18)//if temperature is equal or bigger than 18 degrees
 {
digitalWrite(ledPin,HIGH);//Turn ON LED (as my serial monitor doesn't work I turn on/of the LED)
    
 }
       
       else//if temperature is under 19 degrees
    {
      digitalWrite(ledPin,LOW);//Turn OFF LED
   
    }
  
 }