const int trigPin = 2;
const int echoPin = 3;
const int LEDlampRed = 4;
const int LEDlampYellow = 5;
const int LEDlampGreen = 6;
const int buzzer = 7;
int sound = 500;
long durationInDigit, distanceInCM;

void setup()
{
Serial.begin (9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(LEDlampRed, OUTPUT);
pinMode(LEDlampYellow, OUTPUT);
pinMode(LEDlampGreen, OUTPUT);
pinMode(buzzer, OUTPUT);
}

void loop()
{
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
durationInDigit = pulseIn(echoPin, HIGH);
distanceInCM = (durationInDigit * 0.034) / 2;

if (distanceInCM > 50)
{
digitalWrite(LEDlampGreen, LOW);
digitalWrite(LEDlampYellow, LOW);
digitalWrite(LEDlampRed, LOW);
noTone(buzzer);
}

else if (distanceInCM <= 50 && distanceInCM > 20)
{
digitalWrite(LEDlampGreen, HIGH);
digitalWrite(LEDlampYellow, LOW);
digitalWrite(LEDlampRed, LOW);
noTone(buzzer);
}

else if (distanceInCM <= 20 && distanceInCM > 5)
{
digitalWrite(LEDlampYellow, HIGH);
digitalWrite(LEDlampGreen, HIGH);
digitalWrite(LEDlampRed, LOW);
tone(buzzer, 500);
}

else
{
digitalWrite(LEDlampGreen, HIGH);
digitalWrite(LEDlampYellow, HIGH);
tone(buzzer, 1000);
digitalWrite(LEDlampRed, HIGH);
delay(300);
digitalWrite(LEDlampRed, LOW);
delay(300);
}

Serial.print(distanceInCM);
Serial.println(" cm");

}