int crvLED = 6;
int zelLED = 5;
int sinLED = 4;
int zolLED = 3;
int LDR = A0;
int vrednost;

void setup () {
  pinMode (crvLED, OUTPUT);
  pinMode (zelLED, OUTPUT);
  pinMode (sinLED, OUTPUT);
  pinMode (zolLED, OUTPUT);
  pinMode (LDR, INPUT);
  Serial.begin (9600);
}

void loop () {
  vrednost = analogRead(LDR);
  Serial.println(vrednost);

  if (vrednost > 900) {
    digitalWrite (crvLED, HIGH);
    digitalWrite (zelLED, LOW);
    digitalWrite (sinLED, LOW);
    digitalWrite (zolLED, LOW);
  }

  else if (vrednost > 700 && vrednost <= 900) {
    digitalWrite (crvLED, LOW);
    digitalWrite (zelLED, HIGH);
    digitalWrite (sinLED, LOW);
    digitalWrite (zolLED, LOW);
  }
  else if (vrednost > 500 && vrednost <= 700) {
    digitalWrite (crvLED, LOW);
    digitalWrite (zelLED, LOW);
    digitalWrite (sinLED, HIGH);
    digitalWrite (zolLED, LOW);
  }
  else if (vrednost > 300 && vrednost <= 500) {
    digitalWrite (crvLED, LOW);
    digitalWrite (zelLED, LOW);
    digitalWrite (sinLED, LOW);
    digitalWrite (zolLED, HIGH);
  }
  else {
    digitalWrite (crvLED, LOW);
    digitalWrite (zelLED, LOW);
    digitalWrite (sinLED, LOW);
    digitalWrite (zolLED, LOW);
  }
}