public int CompareTo(object obj) { var b = (Book)obj; var conditionTitle = Titles.CompareTo(b.Titles); if (conditionTitle != 0) { return(conditionTitle); } var conditionPages = Pages.CompareTo(b.Pages); if (conditionPages != 0) { return(conditionPages); } var conditionWords = Words.CompareTo(b.Words); return(conditionWords); }