const int numLED = 4; //menginisialisasikan jumlah LED
const int pinLED[numLED] ={2, 4, 6, 8}; //menginisisalisasikan pin pin LED

void setup() {
  for(int i=0; i<4; i++) //
  {
    pinMode(pinLED[i], OUTPUT);
  }
}

void loop() {
  for(int i=0; i<4; i++)
  {
    digitalWrite(pinLED[i], HIGH);
    delay(500);
  }
  for(int i=4; i>0; i--)
  {
    digitalWrite(pinLED[i], LOW);
    delay(500);
  }
}