#define DEBUG

void setup()
{
  Serial.begin(115200);
  delay(1000);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
 #ifdef DEBUG
 Serial.print("Hello World!!!");
 #endif

 digitalWrite(LED_BUILTIN, HIGH);
 delay(1000);
 digitalWrite(LED_BUILTIN, LOW);
 delay(1000);
}