int led1_2 = 2;
int led3_4 = 3;

void setup() {
  // put your setup code here, to run once:
  pinMode(led1_2, OUTPUT);
  pinMode(led3_4, OUTPUT);
  Serial.begin(9600);
  Serial.println("Hello, ESP32!");
}

void loop() {
  for(int i = 0; i <= 10000; i = i+30){
    digitalWrite(led1_2, HIGH);
    delay(i);
    digitalWrite(led1_2, LOW);
    delay(i);
    digitalWrite(led3_4, HIGH);
    delay(i);
    digitalWrite(led3_4, LOW);
    delay(i);

  }
}