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#include <chrono>
#include <cassert>
#include <string>
#include <array>
#include <deque>
#include <map>
#include <queue>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <iterator>
#include <algorithm>
#include <cmath>
#include <complex>
#include <numeric>
#include <random>
#include <ios>
#include <iostream>
#include <bitset>
#include <iomanip>
using namespace std; 

#define fwd(i, a, b) for (int i = (a); i < (b); ++ i)
#define rep(i, n) for (int i = 0; i < (n); ++ i)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)x.size())
#define st first
#define nd second
#define pii pair<int, int>
#define vi vector<int>
#define fastio ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define ll long long

#ifdef LOCAL
template<typename Stream, typename T1, typename T2>
Stream& operator << (Stream& out, pair<T1, T2> a) {return out << "(" << a.st << ", " << a.nd << ")";}
 
template<typename Stream, typename T>
Stream &operator << (Stream& out, T v) {
	out << "{";
	int i = 0;
	for (auto x : v)
		out << x << ((++ i) != sz(v) ? ", " : "");
	return out << "}";
}

template<typename... Args>
void dump(Args... x) {((cerr << x << ", "), ...) << '\n';}
 
#define debug(x...) cerr << "[" #x "]: ", dump(x)
#else
#define debug(...) 0
#endif

const int maxN = 8;

long long dp[2][(1 << maxN)][maxN + 1][maxN];
long long pp[2][(1 << maxN)][maxN + 1][maxN];
int mc[(1 << maxN)];
int mc2[(1 << maxN)][(1 << maxN)];
int par[2][(1 << maxN)];

bool has(int n, int k) {
	if (n & (1 << k))
		return true;
	return false;
}

int32_t main() {
	fastio;
	int n, m;
	cin >> n >> m;
	int fir = 0;
	int firc = 0;
	rep(i, n)
		rep(j, m) {
			char c;
			cin >> c;
			if (c == 'O') {
				fir ^= ((i + j) & 1);
				++ firc;
			}
		}
	int fin = 0;
	int finc = 0;
	long double findeg = 0;
	vector<string> s(n);
	rep(i, n)
		cin >> s[i];
	rep(i, n)
		rep(j, m) {
			if (s[i][j] == 'O') {
				fin ^= ((i + j) & 1);
				++ finc;
				if (i - 1 >= 0 && s[i - 1][j] == '.')
					findeg += 1;
				if (i + 1 < n && s[i + 1][j] == '.')
					findeg += 1;
				if (j - 1 >= 0 && s[i][j - 1] == '.')
					findeg += 1;
				if (j + 1 < m && s[i][j + 1] == '.')
					findeg += 1;
			}
		}
	if (fin != fir || firc != finc) {
		cout << setprecision(15) << fixed << 0.0 << '\n';
		return 0;
	}
	rep(i, (1 << n)) {
		rep(j, (1 << n)) {
			int p = 0;
			rep(k, n)
				if (has(i, k) != has(j, k))
					++ p;
			mc2[i][j] = p;
		}
		int p = 0;
		int pr1 = 0;
		int pr2 = 0;
		rep(j, n)
			if (has(i, j)) {
				if (has(j, 0))
					++ pr1;
				else
					++ pr2;
			}
		rep(j, n - 1)
			if (has(i, j) != has(i, j + 1))
				++ p;
		mc[i] = p;
		par[0][i] = pr1;
		par[1][i] = pr2;
		dp[pr1 & 1][i][__builtin_popcount(i)][0] = p;
		pp[pr1 & 1][i][__builtin_popcount(i)][0] = 1;
	}
	fwd(i, 1, m)
		rep(p1, 2)
			rep(M1, (1 << n))
				rep(k1, firc + 1)
					rep(M2, (1 << n)) {
						int k = __builtin_popcount(M2);
						int p2 = (mc2[M1][M2] + mc[M2]);
						if (k + k1 <= firc) {
							pp[p1 ^ (par[i & 1][M2] & 1)][M2][k + k1][i] += pp[p1][M1][k1][i - 1];
							dp[p1 ^ (par[i & 1][M2] & 1)][M2][k + k1][i] += dp[p1][M1][k1][i - 1];
							dp[p1 ^ (par[i & 1][M2] & 1)][M2][k + k1][i] += pp[p1][M1][k1][i - 1] * p2;
						}
					}
	long double deg = 0;
	rep(i, (1 << n))
		deg += dp[fin][i][finc][m - 1];
	cout << setprecision(15) << fixed << findeg / deg << '\n';
	return 0;
}