int8_t Pin[] = {2,3,4,5,6,7,8,9,10,11};
int8_t dlzka = sizeof(Pin)/sizeof(int8_t);
int rychlost;
int i=0;
bool stav = true;
unsigned long previousMillis = 0;
void setup() {
  for (int i=0; i<dlzka; i++) {
    pinMode(Pin[i], OUTPUT);
  } 
  Serial.begin(9600);
  Serial.println(dlzka);
}
void loop() { 

  rychlost=map(analogRead(A0),0,1023,50,500);
  Serial.println(rychlost);
  unsigned long currentMillis = millis();
  if(currentMillis - previousMillis >= rychlost){
    previousMillis = currentMillis;
  if(stav){
    digitalWrite(Pin[i++], HIGH);
  }

  else{
    digitalWrite(Pin[i--], LOW);
  }
     
  delay(rychlost);
    if(i>=dlzka || i<=-1){
      stav=!stav;
    }
  }
}