H, W = map(int, input().split())
S = [list(input().rstrip()) for _ in range(H)]
T = [list(input().rstrip()) for _ in range(H)]

for i in range(H):
    S[i] = [list(x) for x in S[i]]
    T[i] = [list(x) for x in T[i]]

def judge(S, T):
    for i in range(H):
        for j in range(W):
            if S[i][j] == T[i][j]:
                return False
    return True

ok1 = judge(S, T)

Sr = [list(x)[::-1] for x in zip(*S)]
Srr = [list(x)[::-1] for x in zip(*Sr)]

ok2 = judge(Srr, T)

# print(ok1, ok2)


if ok1 == True and ok2 == True:
    e = 0
    rem = 1
    for i in range(10**6):
        p = rem * (1 - 2 ** (-i))
        e += p * (i+1)
        rem -= p
        if e > 0 and e < 10**(-7):
            break
elif ok1 == False and ok2 == False:
    e = 0
elif ok1 == True and ok2 == False:
    e = 0
    rem = 1
    for i in range(10**6):
        if i % 2 == 0:
            p = rem * (1 - 2 ** (-i))
        else:
            p = 0
        e += p * (i+1)
        rem -= p
        if e > 0 and e < 10**(-7):
            break
elif ok1 == False and ok2 == True:
    e = 0
    rem = 1
    for i in range(10**6):
        if i % 2 == 1:
            p = rem * (1 - 2 ** (-i))
        else:
            p = 0
        e += p * (i+1)
        rem -= p
        if e > 0 and e < 10**(-7):
            break
print(e)