#define PIN_LED1 5
#define PIN_LED2 19
#define PIN_LED3 4

void setup() {
  // put your setup code here, to run once:
  pinMode(PIN_LED1, OUTPUT);
  pinMode(PIN_LED2, OUTPUT);
  pinMode(PIN_LED3, OUTPUT);
}

void loop() {
  digitalWrite(PIN_LED1, HIGH);
  delay(1000);
  digitalWrite(PIN_LED1, LOW);
  delay(1000);
  digitalWrite(PIN_LED2, HIGH);
  delay(1000);
  digitalWrite(PIN_LED2, LOW);
  delay(1000);
  digitalWrite(PIN_LED3, HIGH);
  delay(1000);
  digitalWrite(PIN_LED3, LOW);
  delay(1000);
}