private void getOptimalSkylines(int x){
        if(x!=0){
            for(int i=0;i<list.size();i++){
                list.getBuilding(i).moveToLeft();
                getOptimalSkylines(x-1);
                list.getBuilding(i).moveToRight();
                list.getBuilding(i).moveToRight();
                getOptimalSkylines(x-1);
                list.getBuilding(i).moveToLeft();
            }
        }else set.add(listToSkyline(list));
    }