Rooks#11797
The rook is a chess piece that moves along the rows and columns of the board.
Fig. 1: example of possible rook moves.
The king of the chess country has issued a new liberal decree stating that each rook must reside on a square chessboard of size N \times N, with an equal number of white and black rooks. Additionally, according to the peacetime code, no piece should be attacked by a piece of the opposite color. A rook is under attack by another rook if they are located in the same row or column. The rooks want to find out how many of them can fit according to the new laws. Can you help them?
Fig. 2: a black rook is under attack by a white rook.
The input consists of a single line containing the number (2 \le N \le 10^4) — the size of the N \times N square chessboard.
Print a single number — the maximum number of rooks of one color.
Example
Fig. 3: example of the placement of 4 white and 4 black rooks on a 4 \times 4 board.