// Include the necessary libraries
#include <Servo.h>

// Define the pins for the HC-SR04 sensor
#define TRIGGER_PIN 2
#define ECHO_PIN 3

// Define the servo pin
#define SERVO_PIN 9

// Define the maximum distance for object detection in cm
#define MAX_DISTANCE 10

// Initialize the servo object
Servo servo;

// Initialize variables for object detection and servo rotation
int objectCount = 0;
int servoAngle = 0;

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);

  // Set the trigger pin as output and echo pin as input
  pinMode(TRIGGER_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // Attach the servo to the servo pin
  servo.attach(SERVO_PIN);

  // Set the initial servo angle to 0 degrees
  servo.write(servoAngle);
}

void loop() {
  // Send a pulse to the trigger pin to start the measurement
  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);

  // Read the duration of the pulse from the echo pin
  long duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate the distance in cm
  int distance = duration * 0.034 / 2;

  // Check if an object is detected within the maximum distance
  if (distance <= MAX_DISTANCE) {
    // Increase the object count
    objectCount++;

    // Print the distance and object count for debugging
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.print(" cm, Object Count: ");
    Serial.println(objectCount);

    // Check if the object count is equal to 3
    if (objectCount == 3) {
      // Rotate the servo to 90 degrees in 1 seconds
      servo.write(90);
      delay(1000);

      // Reset the object count to 0
      objectCount = 0;
    }
  } else {
    // Reset the object count to 0 if no object is detected
    objectCount = 0;
  }
}