int led1=5;
int led2=18;
int led3=19;

 void setup() {
  
   pinMode(led1,OUTPUT);
   pinMode(led2,OUTPUT);
   pinMode(led3,OUTPUT);
   }
   void loop(){
     
     digitalWrite(led1,HIGH);
     delay(1000);
     digitalWrite(led1, LOW);
     delay(1000);
     digitalWrite(led2,HIGH);
     delay(1000);
     digitalWrite(led2,LOW);
     delay(1000);
     digitalWrite(led3,HIGH);
     delay(1000);
     digitalWrite(led3,LOW);
     delay(1000);
     
    
   }