const int LED1 = 2;
const int LED2 = 4;
const int S1 = 13;

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(S1, INPUT_PULLUP);
}

void loop() {
  if(digitalRead(S1) == LOW)
    digitalWrite(LED2, HIGH);
  else
    digitalWrite(LED2, LOW);

  digitalWrite(LED1, HIGH);
  delay(1000);
  digitalWrite(LED1, LOW);
  delay(1000);
}