int led1 = 15;
int led2 = 5;
int led3 = 4;
int led4 = 16;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Hello, ESP32!");
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
// this speeds up the simulation
  digitalWrite(led4, HIGH);
  delay(50);
  digitalWrite(led4, LOW);
  delay(50);

  digitalWrite(led1, HIGH);
  delay(100);
  digitalWrite(led1, LOW);
  delay(100);

  digitalWrite(led3, HIGH);
  delay(150);
  digitalWrite(led3, LOW);
  delay(150);

  digitalWrite(led2, HIGH);
  delay(200);
  digitalWrite(led2, LOW);
  delay(200);
}