int ledr=2;
int ledg=4;
int ledy=7;
int pot=A0;
void setup() {
  // put your setup code here, to run once:
pinMode(ledr, OUTPUT);
pinMode(ledg, OUTPUT);
pinMode(ledy, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
int value=analogRead(pot);
if (value<100){
  red();
}
else if(value>101&&value<300)
{
  green();

}
else if(value>301){
  yellow();
}
}
void red(){
  digitalWrite(ledr, HIGH);
  digitalWrite(ledg, LOW);
  digitalWrite(ledy, LOW);

}
void green(){
  digitalWrite(ledg, HIGH);
  digitalWrite(ledr, LOW);
  digitalWrite(ledy, LOW);

}
void yellow(){
  digitalWrite(ledy, HIGH);
  digitalWrite(ledg, LOW);
  digitalWrite(ledr, LOW);

}