import sys
sys.stdin = open('blackOrWhiteInput.txt', 'r')

def blackOrWhite(n, board):
    t = 0
    b = 0
    w = 0
    for i in range(n):
        for j in range(n):
            if board[i][j] == 'B':
                t = t + 1
                w = 0
                b = b + 1
            else:
                t = t - 1
                b = 0
                w = w + 1
            if b == 3 or b == -3 or w == 3 or w == -3:
                print(0)
                return
        if t != 0:
            print(0)
            return
    for i in range(n):
        for j in range(n):
            if board[j][i] == 'B':
                t = t + 1
                w = 0
                b = b + 1
            else:
                t = t - 1
                b = 0
                w = w + 1
            if b == 3 or b == -3 or w == 3 or w == -3:
                print(0)
                return
        if t != 0:
            print(0)
            return
    print(1)
    return

n = int(input())
board = []
for i in range(n):
    s = input()
    board.append(list(s))

blackOrWhite(n, board)