#define LED_01 2
#define LED_02 4
#define LED_03 5
#define LED_04 18

void setup() {
  pinMode(LED_01, OUTPUT);
  pinMode(LED_02, OUTPUT);
  pinMode(LED_03, OUTPUT);
  pinMode(LED_04, OUTPUT);
}

void loop() {
  digitalWrite(LED_01, HIGH);
  digitalWrite(LED_02, LOW);
  digitalWrite(LED_03, HIGH);
  digitalWrite(LED_04, LOW);
  delay(500);
  digitalWrite(LED_01, LOW);
  digitalWrite(LED_02, HIGH);
  digitalWrite(LED_03, LOW);
  digitalWrite(LED_04, HIGH);
  delay(500);
}