Counting Object of type without counting children objects, possible?

Question

I am trying to count how many of each type of object are in a dictionary to display them, however when counting objects of Amateur type it also counts all the objects of Professional and Celebrity type because they're children of Amateur. Is there anyway to fix this WITHOUT removing the inheritance and just counting objects of only type Amateur?

Sample code:

private void GetTotalEntries()
{
    string amateurEntries;
    string profEntries;
    string celebEntries;

    amateurEntries = manager.competitors.Values.OfType<Amateur>().Count().ToString();
    profEntries = manager.competitors.Values.OfType<Professional>().Count().ToString();
    celebEntries = manager.competitors.Values.OfType<Celebrity>().Count().ToString();

    EntriesTextBox.Text = "Amateur Entries:" + amateurEntries + "\nProfessional Entries:" + profEntries + "\nCelebrity Entries:" + celebEntries;
}

Answer 1

Of course it's possible. For instance using a simple Where (or Count with predicate) with exact type match:

amateurEntries = manager.competitors.Values
    .Where(x => x.GetType() == typeof(Amateur)).Count().ToString();

Answer 2

OfType<T> counts all elements which can be cast to T which is obviously the case for a subclass of T. Assumed, that all of your manager.competitors are either professionals, celebs or amateurs and those sets are distinct, you could count the amateurs indirectly by

int prof = manager.competitors.Values.OfType<Professional>().Count(); 
int  celeb = manager.competitors.Values.OfType<Celebrity>().Count();
int amateurs = manager.competitors.Count() - (prof + celebs)