#define led1 8
#define led2 9
#define led3 10
#define led4 11
#define a 2
#define d 3
void setup()
{
  Serial.begin(9600);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);

}

void loop()
 {
  if(digitalRead((2)) == HIGH)
  {
    int val1 = 8;
    while(val1<=11)
    {
      digitalWrite(val1, HIGH);
      delay(1000);
      digitalWrite(val1, LOW);
      val1 = val1 +1;
    }
  }
  if(digitalRead((3))==HIGH)
  {
    int val2 = 12;
    while(val2>=8)
    {
      digitalWrite(val2, HIGH);
      delay(1000);
      digitalWrite(val2, LOW);
      val2=val2-1;
    }
  }

}