void setup() {
  pinMode(33, OUTPUT);
  pinMode(20, OUTPUT);
  pinMode(18, OUTPUT);
}
void loop()
{
  digitalWrite(33, HIGH);
  delay(50);
  digitalWrite(20, HIGH);
  delay(50);
  digitalWrite(18, HIGH);
  delay(50);
  digitalWrite(33, LOW);
  delay(50);
  digitalWrite(20, LOW);
  delay(50);
  digitalWrite(18, LOW);
  delay(50);
}