int gas = 0;

void setup()
{
  pinMode(A5, INPUT);
  Serial.begin(9600);
  pinMode(4, OUTPUT);
}

void loop()
{
  gas = analogRead(A5);
  Serial.print("Gas : ");
  Serial.println(gas);
  if (gas > 600) {
    digitalWrite(4, HIGH);
    Serial.println("El gas supero los 600");
  } else {
    digitalWrite(4, LOW);
  }
  delay(1000); // Wait for 1000 millisecond(s)
}