const int LED[] = {4,6,9,22};
const int NUM_LEDS = 4;

void setup() {
  for (int i = 0; i < NUM_LEDS; i++) {
    pinMode(LED[i], OUTPUT);
  }
}

void loop() {
  // Blink LEDs from left to right
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(LED[i], HIGH); // Turn on LED
    delay(1000); // Delay for 1 second
    digitalWrite(LED[i], LOW); // Turn off LED
  }
  
  // Blink LEDs from right to left
  for (int i = NUM_LEDS - 1; i >= 0; i--) {
    digitalWrite(LED[i], HIGH); // Turn on LED
    delay(1000); // Delay for 1 second
    digitalWrite(LED[i], LOW); // Turn off LED
  }
}