How to get pagedlist size in android when using paging library with mvvm

please, I'm using android MVVM with retrofit and with paging library and the problem is I can't get size of pagedlist. pagedlist = 0 in UI always.

and the below code that the way how I get the list size.

 private void getAllAds() {
        userHomeViewModel.getHomeAllAdsPagedList().observe(this, new Observer<PagedList<AllAdsModel>>() {
            @Override
            public void onChanged(PagedList<AllAdsModel> list) {
                allAdsModelPagedList = list;
                Toast.makeText(AllAdsActivity.this, ""+list.size(), Toast.LENGTH_SHORT).show();
                //list.size = 0!!!!
                initUserAllAds();
            }
        });
    }