#include <Servo.h>
Servo gate;
#define RLED 4
#define GLED 5 
const int trigPin=6;
const int echoPin=7;
long duration;
long distance;

void setup() {
Serial.begin(9600);
gate.attach(3);
pinMode(RLED,OUTPUT);
pinMode(GLED,OUTPUT);
pinMode(trigPin,OUTPUT);
pinMode(echoPin,INPUT);
}

void loop() {
duration=pulseIn(echoPin,HIGH);
distance=duration*0.034/2;
serial.println(distance);

if(distance<20);
{
  gate.write(0);//gate open 
  digitalWrite(RLED,LOW);
  digitalWrite(GLED,HIGH);
}
else
{
  gate.write(90);//gate close 
  digitalWrite(RLED,HIGH);
  digitalWrite(GLED, LOW);
}
}