const int trigPin = 5;
const int echoPin = 23;
const int led= 33;
const int led2= 32;
const int led3= 27;
const int led4= 26;

#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;
float distanceInch;
bool ledState = LOW;
void setup()
{
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
   pinMode(led, OUTPUT);
   pinMode(led2, OUTPUT);
   pinMode(led3, OUTPUT);
   pinMode(led4, OUTPUT);
   
}
 void loop()
{
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin,HIGH);

distanceCm = duration * SOUND_SPEED/2;

distanceInch = distanceCm * CM_TO_INCH;

Serial.print("Distance(cm): ");
Serial.println(distanceCm);
Serial.print("Distance(inch): ");
Serial.println(distanceInch);

delay(1000);
if (distanceCm < 20) {
    
    digitalWrite(led, HIGH);
    delay(300); 
    digitalWrite(led2, HIGH);
    delay(300); 
    digitalWrite(led, LOW);
    digitalWrite(led2, LOW);
    delay(300); 
  } else {
    
    digitalWrite(led3, HIGH);
    delay(300); 
    digitalWrite(led4, HIGH);
    delay(300); 
    digitalWrite(led3, LOW);
    delay(300); 
    digitalWrite(led4, LOW);
    delay(300); 
  }


}