CF961C.Chessboard

普及/提高-

通过率:0%

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题目描述

Magnus decided to play a classic chess game. Though what he saw in his locker shocked him! His favourite chessboard got broken into 44 pieces, each of size nn by nn , nn is always odd. And what's even worse, some squares were of wrong color. jj -th square of the ii -th row of kk -th piece of the board has color ak,i,ja_{k,i,j} ; 11 being black and 00 being white.

Now Magnus wants to change color of some squares in such a way that he recolors minimum number of squares and obtained pieces form a valid chessboard. Every square has its color different to each of the neightbouring by side squares in a valid board. Its size should be 2n2n by 2n2n . You are allowed to move pieces but not allowed to rotate or flip them.

输入格式

The first line contains odd integer nn (1<=n<=100)(1<=n<=100) — the size of all pieces of the board.

Then 44 segments follow, each describes one piece of the board. Each consists of nn lines of nn characters; jj -th one of ii -th line is equal to 1 if the square is black initially and 0 otherwise. Segments are separated by an empty line.

输出格式

Print one number — minimum number of squares Magnus should recolor to be able to obtain a valid chessboard.

输入输出样例

  • 输入#1

    1
    0
    
    0
    
    1
    
    0
    

    输出#1

    1
    
  • 输入#2

    3
    101
    010
    101
    
    101
    000
    101
    
    010
    101
    011
    
    010
    101
    010
    

    输出#2

    2
    
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