const int POTENCIOMETR = 0;
const int LED1 = 2;
const int LED2 = 3;
const int LED3 = 4;
const int LED4 = 5;
const int LED5 = 6;

float napeti, blinkDelay;

void setup() {
 Serial.begin(9600);
 pinMode(LED1, OUTPUT);
 pinMode(LED2, OUTPUT);
 pinMode(LED3, OUTPUT);
 pinMode(LED4, OUTPUT);
 pinMode(LED5, OUTPUT);

 digitalWrite(LED1, LOW);
 digitalWrite(LED2, LOW);
 digitalWrite(LED3, LOW);
 digitalWrite(LED4, LOW);
 digitalWrite(LED5, LOW);
}

void loop() {
 napeti = analogRead(POTENCIOMETR);
 napeti = napeti * 5 / 1024;
  
  /*
  blinking speed based on potentiometer
  
  blinkDelay = analogRead(POTENCIOMETR) * 5;
  digitalWrite(LED5, HIGH);
  delay(blinkDelay/2);
  digitalWrite(LED5, LOW);
  delay(blinkDelay/2);
  */

 if (napeti < 1) {
  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);
  digitalWrite(LED3, LOW);
  digitalWrite(LED4, LOW);
 }
 
 if (napeti > 1 && napeti < 2) {
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
    digitalWrite(LED4, LOW);
 }

  if (napeti > 2 && napeti < 3) {
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, LOW);
    digitalWrite(LED4, LOW);
 }

  if (napeti > 3 && napeti < 4) {
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, HIGH);
    digitalWrite(LED4, LOW);
 }

  if (napeti > 4) {
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, HIGH);
    digitalWrite(LED4, HIGH);
 }
}