Which of the following operations do bidirectional iterators have?

a. Prefix operator* to make available the container element for use as l-value or r-value.
b. Overloaded operator+ to add an int value to the iterator to move the place the iterator points forward by the argument number of elements.
c. Overloaded operator* to multiply the iterator by an int value to move the place the iterator points by a number of elements equal to the argument.
d. Overloaded operator++ to move the place the iterator points forward by one element.
e. Overloaded operator-- to move the place the iterator points backward by one element.
f. Overloaded operator== and operator!= to determine whether two iterators point to the same element.

Part a), d), e) and f) are correct.