int mypin = A2;
int readvalue=0;
float volts=0;
int wait=500;
int redpin = 7;
int yellowpin=8;
int greenpin=9;
void setup() {
  // put your setup code here, to run once:

Serial.begin(9600);
pinMode(redpin, OUTPUT);
pinMode(yellowpin, OUTPUT);
pinMode(greenpin, OUTPUT);
pinMode(mypin, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
readvalue=analogRead(mypin);
volts=(5.0/1023.0)*readvalue;
Serial.println(volts);
if(volts>4.0){
   digitalWrite(redpin, HIGH);
}
//if(volts<4.0)
else{
  digitalWrite(redpin, LOW);
}
if(volts<=4.0 && volts>=2.0){
  digitalWrite(yellowpin, HIGH);
}
else{
  digitalWrite(yellowpin, LOW);
}
if(volts<2.0){
   digitalWrite(greenpin, HIGH);
}
else{
  digitalWrite(greenpin, LOW);
}
delay(wait);
}