def solve(H, W, Ss, Ts):
    odd = all(S + T + 1 == 1 << W for S, T in zip(Ss, Ts))
    even = all(S + T + 1 == 1 << W for S, T in zip(Ss[::-1], Ts))

    E = []
    p = 1.0
    for i in range(1, 20202020):
        if i & 1:
            if odd:
                e = i * p * (1.0 - pow(2, -i + 1))
                E.append(e)
                p *= pow(2, -i + 1)
        else:
            if even:
                e = i * p * (1.0 - pow(2, -i + 1))
                E.append(e)
                p *= pow(2, -i + 1)

    ans = sum(E[::-1])

    return ans


def main():
    H, W = map(int, input().split())
    Ss = []
    for _ in range(H):
        line = input()
        line = line.replace(".", "0").replace("#", "1")
        Ss.append(int(line, 2))
    Ts = []
    for _ in range(H):
        line = input()
        line = line.replace(".", "0").replace("#", "1")
        Ts.append(int(line, 2))
    ans = solve(H, W, Ss, Ts)
    print(ans)


if __name__ == "__main__":
    main()