938 B | 938 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from decimal import Decimal
BLANK = " "
#inp = input
inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def f(n, l):
for i in range(n):
if l[i].count("W") != l[i].count("B"):
return False
for i in range(n):
d = 0
for j in range(n):
if l[j][i] == "W":
d += 1
if d * 2 != n:
return False
for i in range(n):
for j in range(n - 2):
if l[i][j] == l[i][j + 1] == l[i][j + 2]:
return False
if l[j][i] == l[j + 1][i] == l[j + 2][i]:
return False
return True
def solve():
n = ii()
l = [input() for _ in range(n)]
p(1 if f(n, l) else 0)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()