void setup() 
{
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(5, OUTPUT);
}

void loop() 
{
  for (int i = 1; i <= 10; i++)
  {
    digitalWrite(LED_BUILTIN, HIGH);
    digitalWrite(5, LOW);
    delay(1000);
    digitalWrite(LED_BUILTIN, LOW);
    digitalWrite(5, HIGH);
    delay(1000);
  }
  while(true);
}