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// while (clock()<=69*CLOCKS_PER_SEC)
// #pragma comment(linker, "/stack:200000000")
// #pragma GCC optimize("O3")
// #pragma GCC target ("avx2")
// #pragma GCC optimize("Ofast")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
// #pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set =
    tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define sim template <class c
#define ris return *this
#define dor > debug &operator<<
#define eni(x)                                                                    \
    sim > typename enable_if<sizeof dud<c>(0) x 1, debug &>::type operator<<(c i) \
    {
sim > struct rge {
    c b, e;
};
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c *x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef XOX
    ~debug()
    {
        cerr << endl;
    }
    eni(!=) cerr << boolalpha << i;
    ris;
} eni(==) ris << range(begin(i), end(i));
}
sim, class b dor(pair<b, c> d)
{
    ris << "" << d.first << " --> " << d.second << "";
}
sim dor(rge<c> d)
{
    *this << "[";
    for(auto it = d.b; it != d.e; ++it)
        *this << ", " + 2 * (it == d.b) << *it;
    ris << "]";
}
#else
    sim dor(const c &)
    {
        ris;
    }
#endif
}
;
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#ifdef XOX
#warning Times may differ!!!
#endif

#define endl '\n'
#define pb emplace_back
#define vt vector
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int nax = 1e6, mod = 1e9 + 7;

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    int n, m;
    cin >> n >> m;
    if(n == m && n == 1) {
        cout << 1 << endl;
        exit(0);
    }
    int kk = 0;
    vt<int> par(2);
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            cerr << ((i + j) % 2) << " ";
        }
        cerr << endl;
    }
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            char c;
            cin >> c;
            if(c == 'O') {
                par[(i + j) % 2]++;
            }
        }
    }
    debug() << imie(par);
    vt<vt<char>> g(n + 1, vt<char>(m + 1));
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            cin >> g[i][j];
            if(g[i][j] == 'O') {
                kk++;
                par[(i + j) % 2]--;
            }
        }
    }
    debug() << imie(par);
    if(par[0] % 2 || par[1] % 2) {
        cout << 0 << endl;
        exit(0);
    }
    vt<int> dx{0, 0, +1, -1}, dy{+1, -1, 0, 0};
    int ruch = 0;
    auto ing = [&](int x, int y) {
        return (1 <= x && x <= n && 1 <= y && y <= m);
    };
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            for(int k = 0; k < 4; k++) {
                if(g[i][j] == '.') {
                    continue;
                }
                auto [hx, hy] = make_pair(i + dx[k], j + dy[k]);
                if(ing(hx, hy) && g[hx][hy] == '.') {
                    ruch++;
                }
            }
        }
    }
    if(ruch == 0) {
        cout << 1 << endl;
        exit(0);
    }
    auto po = [&](int n, int k) {
        long double res = 1;
        for(int i = 1; i <= n; i++) {
            res *= i;
        }
        for(int i = 1; i <= k; i++) {
            res /= i;
        }
        for(int i = 1; i <= n - k; i++) {
            res /= i;
        }
        return res;
    };
    long double ret = ruch;
    debug() << imie(ret);
    debug() << imie(po(n * m - 2, kk - 1));
    ret /= po(n * m - 2, kk - 1);
    debug() << imie(ret);
    ret /= (n * (m - 1) + m * (n - 1));
    debug() << imie(ret);
    cout << fixed << setprecision(15) << ret << endl;
}