int ledRed = 4;
int ledYellow = 2;
int ledGreen = 3;
int trigger = 12;
int echo = 13;



void setup() {
  // put your setup code here, to run once:
  pinMode(ledRed, OUTPUT);
  pinMode(ledYellow, OUTPUT);
  pinMode(ledGreen, OUTPUT);
  pinMode(trigger, OUTPUT);
  pinMode(echo, INPUT);

  Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(trigger, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigger, LOW);

  digitalWrite(ledRed, LOW);
  digitalWrite(ledYellow, LOW);
  digitalWrite(ledGreen, LOW);

  int duration = pulseIn(echo, HIGH);
  Serial.print("Distance in CM: ");
  int razdalja = duration/58;
  Serial.println(razdalja);

  if (razdalja > 250) {
    digitalWrite(ledRed, LOW);
    digitalWrite(ledYellow, LOW);
    digitalWrite(ledGreen, HIGH);
  }

  else if (razdalja < 250 && razdalja >= 100) {
    digitalWrite(ledRed, LOW);
    digitalWrite(ledYellow, HIGH);
    digitalWrite(ledGreen, LOW);
  }

  else if (razdalja < 100) {
    digitalWrite(ledRed, HIGH);
    digitalWrite(ledYellow, LOW);
    digitalWrite(ledGreen, LOW);
  }

  else {
    digitalWrite(ledRed, LOW);
    digitalWrite(ledYellow, LOW);
    digitalWrite(ledGreen, LOW);
  }

  delay(50);

}