int green = 2;
int yellow = 5;
int red = 8;
void setup() {
  pinMode(A0, INPUT);
    Serial.begin(9600);
    pinMode(green , OUTPUT);
    pinMode(yellow , OUTPUT);
    pinMode(red , OUTPUT);
}

void loop() {
  int vol = analogRead(A0);
  Serial.println(vol);

  if ((vol>=300) && (vol<=500 )) 
    {
      digitalWrite(green , 1);
    }
  else
    {
      digitalWrite(green , 0);  
    }
  
  if ((vol>=600) &&(vol<=800))
    {
      digitalWrite(yellow ,1);
    }
  else
    { 
      digitalWrite(yellow , 0);
    }  
  
  if ((vol >=900) && (vol<=1000))
    {
      digitalWrite(red, 1);
    }
  else 
    {
      digitalWrite(red, 0);
    } 
  delay(1000);
}