long randNumber;
long randNumber2;
long randNumber3;
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(12, OUTPUT);
   pinMode(11, OUTPUT);
}

void loop() {
randNumber = random(10, 500);
randNumber2 = random(10, 500);
randNumber3 = random(10, 500);
digitalWrite(LED_BUILTIN, HIGH);
delay(randNumber);
digitalWrite(LED_BUILTIN, LOW);
delay(randNumber);

digitalWrite(12, HIGH);
delay(randNumber2);
digitalWrite(12, LOW);
delay(randNumber2);

digitalWrite(11, HIGH);
delay(randNumber3);
digitalWrite(11, LOW);
delay(randNumber3);
}