const int trigPin = 7;
const int echoPin = 8;
const int buzzer = 13;

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(buzzer, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
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>40)
{ digitalWrite(3,HIGH);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
delay(500);
} else if (distance<15)
{ digitalWrite(3,LOW);
digitalWrite(4, HIGH);
digitalWrite(5, LOW);
tone(12, 300, 25);
delay(500); }
else {
digitalWrite(3,LOW);
digitalWrite(4, LOW);
digitalWrite(5, HIGH);
tone(buzzer, 626, 250);
delay(500); }
}