void setup() {
  pinMode(16, OUTPUT);
  pinMode(17, OUTPUT);
  pinMode(18, OUTPUT);
  pinMode(19, OUTPUT);

  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
}

int pinLED;

void Blink(int pinLED){
  digitalWrite(pinLED, LOW);
  digitalWrite(pinLED, HIGH);
  delay(1000);
  digitalWrite(pinLED, LOW);
}

void loop() {
  pinLED = random(16, 19);
  Blink(pinLED);
}