int pins[] = {5, 17, 16, 4};

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  for(int i = 0; i < 4; i++) {
    pinMode(pins[i], OUTPUT);
  }
  

  digitalWrite(5, HIGH);
}

void loop() {
  for(int i = 0; i < 4; i++) {
    digitalWrite(pins[i], HIGH);
    delay(300);
  }
  for(int i = 0; i < 4; i++) {
    digitalWrite(pins[i], LOW);
    delay(300);
  }
}