#include <Servo.h>

Servo servo;
#define trig 4
#define echo 5

int ultrasonic() {
  digitalWrite(trig, LOW);
  delayMicroseconds(2);            // Corrected the delay before triggering the HIGH signal
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  int duration = pulseIn(echo, HIGH);
  int distance = (duration / 2) * 0.034;
  return distance;
}

void setup() {
  servo.attach(3);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  Serial.begin(9600);
}

void loop() {
  int d = ultrasonic();            // Corrected function name spelling
  Serial.println(d);
  delay(1000);
  
  if (d < 13) {
    servo.write(90);
    delay(1000);
    servo.write(0);
    delay(1000);
    servo.write(90);
    delay(1000);
    servo.write(180);
    delay(1000);
  }
}