Arduino Programme

int potPin = 0;
float temperature = 0;
int redLED=12;
int yellowLED=11;
int greenLED=10;
long val=0;
void setup()
{ pinMode(redLED, OUTPUT);
pinMode(yellowLED, OUTPUT);
pinMode(greenLED, OUTPUT);
Serial.begin(9600);
Serial.println("LM35 Thermometer"); }
void loop ()
{
val = analogRead(potPin);
temperature = (val*500/1024);
Serial.println ((long)temperature);
if (temperature >= 30)
{
digitalWrite (redLED, HIGH);
digitalWrite (yellowLED, LOW);
digitalWrite (greenLED, LOW);
}
else if ((temperature >=29) && (temperature <30))
{
digitalWrite (redLED, LOW);
digitalWrite (yellowLED, HIGH);
digitalWrite (greenLED, LOW);
}
else
{
digitalWrite (redLED, LOW);
digitalWrite (yellowLED, LOW);
digitalWrite (greenLED, HIGH);
}
delay(2000);
}