const int trigPin = 2;
const int echoPin = 3;
int buzzer = 4;

void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(buzzer, OUTPUT);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);

  int distance = duration *0.0343 / 2;

  Serial.print("Distance ");
  Serial.print(distance);
  Serial.println(" CM");

  if (distance > 200) {
    digitalWrite(6, HIGH);
    digitalWrite(7, LOW);
    digitalWrite(8, LOW);
    digitalWrite(buzzer, 0);

  } else if (distance > 100) {
      if (distance > 100) {
        digitalWrite(6, LOW);
        digitalWrite(7, HIGH);
        digitalWrite(8, LOW);
        digitalWrite(7, LOW);
      }

    digitalWrite(buzzer, 1);
    tone(buzzer, 5000, 400);
    delay(400);
    digitalWrite(buzzer, 0);
    tone(buzzer, 5000, 400);
    delay(400);

  } else {
      if (distance <= 99) {
        digitalWrite(6, LOW);
        digitalWrite(7, LOW);
        digitalWrite(8, HIGH);
        digitalWrite(8, LOW);
      }

    digitalWrite(buzzer, 1);
    tone(buzzer, 1000, 100);
    delay(100);
    digitalWrite(buzzer, 0);
    tone(buzzer, 1000, 100);
    delay(100);
  }

  delay(100);
}