int red=2;
int yellow=8;
int green=13;
int sensor;
int sensorpin=A5;

void setup() {
pinMode(red, OUTPUT);
pinMode(yellow, OUTPUT);
pinMode(green , OUTPUT);
Serial.begin(9600);

}

void loop() {
sensor=analogRead(sensorpin);
Serial.println(sensor);
delay(100);

if((sensor>100)&&(sensor<400))
{digitalWrite(red, HIGH);
digitalWrite(yellow, LOW);
digitalWrite(green, LOW);
}
else if((sensor>=400)&&(sensor<800)){
  digitalWrite(red, LOW);
  digitalWrite(yellow, HIGH);
  digitalWrite(green, LOW);
}
else if(sensor>=800){
digitalWrite(red, LOW);
digitalWrite(yellow, LOW);
digitalWrite(green, HIGH);
}
else{
 digitalWrite(red, LOW); 
 digitalWrite(yellow , LOW);
 digitalWrite(green, LOW);
}
}