iterator_traits<InputIterator>::distance_type
count (InputIterator first, InputIterator last, const T& value);
iterator_traits<InputIterator>::distance_type
count_if (InputIterator first, InputIterator last, Predicate pred);
void count (InputIterator first, InputIterator last,
const T&, Size &);
void count_if (InputIterator first, InputIterator last,
Predicate, Size &);
(후자의 경우 표준에서 채택되었는지 확인할 것!)