static void LambadaSorting(Student[] someArrOfStudents)
 {
     var arrAfterSort = someArrOfStudents.OrderByDescending(x => x.firstName).ThenByDescending(x => x.lastName);
     foreach (var student in arrAfterSort)
     {
         Console.WriteLine("{0} {1}",student.firstName,student.lastName);
     }
 }