21191번 - This Ain't Your Grandpa's Checkerboard 다국어

문제

You are given an $n$-by-$n$ grid where each square is colored either black or white. A grid is correct if all of the following conditions are satisfied:

• Every row has the same number of black squares as it has white squares.
• Every column has the same number of black squares as it has white squares.
• No row or column has 3ドル$ or more consecutive squares of the same color.

Given a grid, determine whether it is correct.

입력

The first line contains an integer $n$ (2ドル\le n\le 24$; $n$ is even). Each of the next $n$ lines contains a string of length $n$ consisting solely of the characters 'B' and 'W', representing the colors of the grid squares.

출력

If the grid is correct, print the number 1ドル$ on a single line. Otherwise, print the number 0ドル$ on a single line.

제한

힌트