#define LED 2

void setup() {
  // put your setup code here, to run once:
  pinMode(2, OUTPUT);
  pinMode (4,OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(2, HIGH);
  delay(100); // this speeds up the simulation
  digitalWrite(4,LOW);
  delay(500);
  digitalWrite(2, LOW);
  digitalWrite(4, HIGH);
  delay (500);
}