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#include <bits/stdc++.h>
#define dbg(x) #x << " = " << x << " "
using ld = long double;
using ll = long long;
using namespace std;
using State = vector<vector<int>>;

int n, m;
int start_par, end_par;

ll dp[2][64][2][1 << 8];
ll cnts[2][64][2][1 << 8];
int pawn_cnt;
ll sum_somsiady[2];
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};
int max_cnt;
int dp_id = 0;

void transition(int height, int width, int cnt, int parity, int mask) {
    // Jeśli biorę kafelek do którego teraz rozszerzam.
    int delta_horizontal = 0;
    int take = (mask >> width & 1);
    dp[dp_id][cnt][parity][mask] = -1;
    cnts[dp_id][cnt][parity][mask] = -1;
    if (cnt < __builtin_popcount(mask)) {
        return;
    }

    if (width > 0) delta_horizontal = take ^ (mask >> (width - 1) & 1);
    int old_parity = (parity + take * (height + width)) % 2;
    // Case 1: W poprzednim separatorze nade mną nie było kafelka.
    // Case 2: W poprzednik separatorze nade mną jest kafelek
    int prev_mask = mask - take * (1 << width);
    ll delta = delta_horizontal + take;
    for (int i = 0; i < 2; i++) {
        ll prev_dp = dp[1 - dp_id][cnt - take][old_parity][prev_mask];
        if (prev_dp >= 0) {
            if (dp[dp_id][cnt][parity][mask] < 0) dp[dp_id][cnt][parity][mask] = 0;
            if (cnts[dp_id][cnt][parity][mask] < 0) cnts[dp_id][cnt][parity][mask] = 0;
            cnts[dp_id][cnt][parity][mask] += cnts[1 - dp_id][cnt - take][old_parity][prev_mask];

            ll change = prev_dp + delta * cnts[1 - dp_id][cnt - take][old_parity][prev_mask];
            dp[dp_id][cnt][parity][mask] += change;

            // cerr << "add " << i << "->" << change << "\n";
        }

        // Przejdź na drugi case.
        prev_mask ^= (1 << width);
        delta = delta_horizontal + (1 - take);
    }

    // cerr << dbg(max_cnt) << dbg(cnt) << dbg(parity) << dbg(mask) << dbg(old_parity)
    //      << dbg(dp[dp_id][cnt][parity][mask]) << dbg(cnts[dp_id][cnt][parity][mask]) << "\n";
}

int32_t main() {
    cin >> n >> m;

    State start_state(n + 1, vector<int>(m + 1, 0)), end_state(n + 1, vector<int>(m + 1, 0));
    for (int i = 0; i < n; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < m; j++) {
            start_state[i][j] = (s[j] == 'O');
            if (start_state[i][j]) {
                pawn_cnt++;
                start_par = (start_par + i + j) % 2;
            }
        }
    }

    for (int i = 0; i < n; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < m; j++) {
            end_state[i][j] = (s[j] == 'O');
            if (end_state[i][j]) {
                end_par = (end_par + i + j) % 2;
            }
        }
    }

    if (start_par != end_par) {
        cout << "0\n";
        return 0;
    }

    max_cnt = n;

    for (int cnt = 0; cnt < 64; cnt++) {
        for (int parity = 0; parity < 2; parity++) {
            for (int mask = 0; mask < (1 << n); mask++) {
                dp[0][cnt][parity][mask] = dp[1][cnt][parity][mask] = -1;
                cnts[0][cnt][parity][mask] = cnts[1][cnt][parity][mask] = -1;
            }
        }
    }

    // Wyliczamy przypadki bazowe
    for (int mask = 0; mask < (1 << n); mask++) {
        int cnt = 0, parity = 0;
        for (int width = 0; width < n; width++) {
            int take = (mask >> width & 1);
            if (take) cnt++;
            parity = (parity + take * width) % 2;
        }

        dp[dp_id][cnt][parity][mask] = 0;
        cnts[dp_id][cnt][parity][mask] = 1;
        for (int width = 0; width < n; width++) {
            int take = (mask >> width & 1);
            if (!take) continue;
            if (width > 0) {
                dp[dp_id][cnt][parity][mask] += (take ^ (mask >> (width - 1) & 1));
            }

            if (width + 1 < n) {
                dp[dp_id][cnt][parity][mask] += (take ^ (mask >> (width + 1) & 1));
            }
        }

        // cerr << dbg(mask) << dbg(cnt) << dbg(parity) << dbg(dp[dp_id][cnt][parity][mask]) <<
        // "\n";
    }

    // Tu chyba sie ma zaczac od height=1, a pierwszy wiersz pałka.
    for (int height = 1; height < m; height++) {
        for (int width = 0; width < n; width++) {
            max_cnt++;
            dp_id = 1 - dp_id;
            for (int cnt = 0; cnt <= min(max_cnt, pawn_cnt); cnt++) {
                for (int parity = 0; parity < 2; parity++) {
                    for (int mask = 0; mask < (1 << n); mask++) {
                        transition(height, width, cnt, parity, mask);
                    }
                }
            }
        }
    }

    for (int mask = 0; mask < (1 << n); mask++) {
        for (int parity = 0; parity < 2; parity++) {
            sum_somsiady[parity] += max(0LL, dp[dp_id][pawn_cnt][parity][mask]);
        }
    }

    ll somsiady_end = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            for (int dir = 0; dir < 4; dir++) {
                int nx = i + dx[dir];
                int ny = j + dy[dir];
                if (nx < 0 || nx >= n || ny < 0 || ny >= m) {
                    continue;
                }

                somsiady_end += (end_state[i][j] && !end_state[nx][ny]);
            }
        }
    }

    // cerr << dbg(somsiady_end) << dbg(sum_somsiady[end_par]) << "\n";
    cout << fixed << setprecision(15) << (ld)somsiady_end / sum_somsiady[end_par] << "\n";
}