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import math

(n, m) = tuple(map(int, input().split()))

def parity(T):
	ret = 0
	for i in range(n):
		cur = i&1
		for j in range(m):
			if T[i][j] == 'O' and cur == 0:
				ret ^= 1
			cur ^= 1
	return ret

def getDeg(T):
	ret = 0
	for i in range(n):
		for j in range(m):
			if i != 0 and T[i][j] != T[i-1][j]:
				ret += 1
			if j != 0 and T[i][j] != T[i][j-1]:
				ret += 1
	return ret

def getK(T):
	ret = 0
	for line in T:
		ret += line.count('O')
	return ret

T = []

for i in range(n):
	T.append(input())
	
par0 = parity(T)

mtLine = input()

for i in range(n):
	T[i] = input()
	
par1 = parity(T)
k = getK(T)
d = getDeg(T)
s = math.comb(n*m-2, k-1) * (n*m*2 - n - m)

res = par0 == par1 and d / s or 0
print('{0:.16f}'.format(res))