// C++ code
//
void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
  digitalWrite(LED_BUILTIN, HIGH);
  delay(1000 * random(1, 5 + 1)); // Wait for 1000 * random(1, 5 + 1) millisecond(s)
  digitalWrite(LED_BUILTIN, LOW);
  delay(1000 * random(1, 5 + 1)); // Wait for 1000 * random(1, 5 + 1) millisecond(s)
}