codeforces#P961C. Chessboard
Chessboard
Description
Magnus decided to play a classic chess game. Though what he saw in his locker shocked him! His favourite chessboard got broken into 4 pieces, each of size n by n, n is always odd. And what's even worse, some squares were of wrong color. j-th square of the i-th row of k-th piece of the board has color ak, i, j; 1 being black and 0 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 2n by 2n. You are allowed to move pieces but not allowed to rotate or flip them.
The first line contains odd integer n (1 ≤ n ≤ 100) — the size of all pieces of the board.
Then 4 segments follow, each describes one piece of the board. Each consists of n lines of n characters; j-th one of i-th line is equal to 1 if the square is black initially and 0 otherwise. Segments are separated by an empty line.
Print one number — minimum number of squares Magnus should recolor to be able to obtain a valid chessboard.
Input
The first line contains odd integer n (1 ≤ n ≤ 100) — the size of all pieces of the board.
Then 4 segments follow, each describes one piece of the board. Each consists of n lines of n characters; j-th one of i-th line is equal to 1 if the square is black initially and 0 otherwise. Segments are separated by an empty line.
Output
Print one number — minimum number of squares Magnus should recolor to be able to obtain a valid chessboard.
Samples
1
0
0
1
0
1
3
101
010
101
101
000
101
010
101
011
010
101
010
2