int x=3; //s2 button
int y=2; //s1 button
int led[8]={11,12,13,14,15,16,17,18};
int s1,s2;
int j=0;


void setup()
{
  pinMode(3, INPUT);
  pinMode(2, INPUT);
  for(int i=0;i<8;i++)
  pinMode(led[i], OUTPUT);
  digitalWrite(led[j],HIGH); // first led will be turned on
}


void loop()
{
  s2 = digitalRead(x); //to right
  s1 = digitalRead(y); //to left

   // if s2 is pressed then it will go right
  if (s2 == HIGH) {
    digitalWrite(led[j],LOW);
    j=j+1;
    if(j>7) //end of the array
      j=7;
    if(j<0) //the other end of the array
      j=2;
    digitalWrite(led[j], HIGH);
    delay(500);
    }

  if (s1 == HIGH) { // if s1 is press then it will go to left
    digitalWrite(led[j],LOW);
    j=j-1;
    if(j>7) //end of the array
      j=0;
    if(j<0) //the other end of the array
      j=0;
    digitalWrite(led[j], HIGH);
    delay(500);
  }
}