Maximum number of Kings on a Chessboard

Given a 8×8 chessboard, what is the maximum number of kings that can be placed on the chessboard so that no two kings attack each other, i.e., none of the kings is under check. A king can move only one step at a time any direction on the chessboard : horizontally, vertically and diagonally.

The Answer is an integer. Just put the number without any decimal places.