void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!,simulation testing");
  pinMode(12, OUTPUT);
  pinMode(25, OUTPUT);
  pinMode(18, OUTPUT);
  pinMode(19, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
   for( int i=0;i<4;i++)
   {if(i%4==0){
    Serial.println( "first led working");
     digitalWrite(12, HIGH);
    delay(300);
    digitalWrite(12, LOW);
    delay(300);
   }
    if(i%4==1){
    Serial.println( "second led working");
     digitalWrite(25, HIGH);
    delay(300);
    digitalWrite(25, LOW);
    delay(300);
    }
    if(i%4==2){
    Serial.println( "third led working");
     digitalWrite(18, HIGH);
    delay(300);
    digitalWrite(18, LOW);
    delay(300);
    }
    if(i%4==3){
    Serial.println( "fourth led working");
     digitalWrite(19, HIGH);
    delay(300);
    digitalWrite(19, LOW);
    delay(300);
    }
   }
}