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#include <iostream>
#include <vector>
#include <iomanip>

using namespace std;

// #define DEBUG
#ifdef DEBUG
#define dassert(x) assert(x);
#define df(...) printf(__VA_ARGS__)
#else
#define dassert(x)
#define df(...)
#endif

#define x first
#define y second
#define mp make_pair
#define pb push_back
#define ir(x, a, b) ((a) <= (x) && (x) <= (b))
#define vec vector
#define sz(x) (ll)x.size()
#define foru(i, n) for (ll i = 0; (i) < (n); ++(i))
#define all(x) (x).begin(), (x).end()
#define fori(i, a, b) for (ll i = (a); i <= (b); ++i)

typedef int64_t ll;

int read() {
    int n = 0; bool b = 0; char c = getchar();
    for (; !ir(c, '0', '9'); c = getchar()) b = (c == '-');
    for (; ir(c, '0', '9'); c = getchar()) n = 10*n + (c-'0');
    if (b) return -n;
    return n;
}

int moves(int n, int m, vec<vec<bool>> a) {
    int s = 0;
    foru (x, n) foru (y, m) {
        if (a[x][y]) {
            fori (dx, -1, 1) fori (dy, -1, 1) {
                if ((dx == 0) + (dy == 0) != 1) continue;
                if (ir(x+dx, 0, n-1) && ir(y+dy, 0, m-1) && !a[x+dx][y+dy]) {
                    // cout << x << " " << y << " " << x+dx << " " << y+dy << "\n";
                    ++s;
                }
            }
        }
    }
    return s;
}

// int n, m;
// int ct[10];
// vec<vec<bool>> a;
// void bt(int x, int y, int on = 0) {
//     if (y == m) {
//         ct[on] += moves(n, m, a);
//         return;
//     }
//     if (x == n) {
//         bt(0, y+1, on);
//         return;
//     }
//     a[x][y] = 0;
//     bt(x+1, y, on);
//     a[x][y] = 1;
//     bt(x+1, y, on+1);
// }

ll choose(ll a, ll b) {
    if (b < a-b) return choose(a, a-b);
    __int128 x = 1; 
    for (__int128 m = b+1; m <= a; ++m) x *= m;
    for (__int128 m = 2; m <= a-b; ++m) x /= m;
    return x;
}

ll calc(ll n, ll m, ll k) {
    if (n < m) swap(n, m);
    // n >= m
    ll s = 0;
    if (m == 1) {
        // cout << "special case" << endl;
        fori (corners, 0, min(k, ll(2))) {
            ll mid = k - corners;
            // cout << corners << " " << mid << " " << n-2 << endl;
            if (mid > n-2) continue;
            ll ways = choose(2, corners)*choose(n-2, mid);
            s += ways * (corners*1 + mid*2);
            // cout << "ways: " << ways << endl;
        }
        return s;
    }
    ll ne = 2*(n+m-4), nm = (n-2)*(m-2);
    // cout << ne << " " << nm << endl;
    fori (corners, 0, min(k, ll(4))) {
        fori (edges, 0, min(k-corners, ne)) {
            ll mid = k - edges - corners;
            if (mid > nm) continue;
            // cout << corners << " " << edges << " " << mid << endl;
            ll ways = choose(4, corners)*choose(ne, edges)*choose(nm, mid);
            s += ways * (corners*2 + edges*3 + mid*4);
            // cout << choose(4, corners)*choose(ne, edges)*choose(nm, mid) << endl;
        }
    }
    return s;
}

int count(int n, int m, vec<vec<bool>> a) {
    int s = 0;
    foru (x, n) foru (y, m) {
        if (a[x][y]) {
            ++s;
        }
    }
    return s;
}

bool bit(int n, int m, vec<vec<bool>> a) {
    bool s = 0;
    foru (x, n) foru (y, m) {
        if (a[x][y]) {
            s ^= (y&1) ^ (x&1);
        }
    }
    return s;
}

int main() {
    df("debug mode\n");
#ifndef DEBUG
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#endif
    // for (int i = 1; i <= 8; ++i) {
    //     cout << choose(64, i) << endl;
    // }
    int n, m;
    cin >> n >> m;
    vec<vec<bool>> t(n, vec<bool>(m));
    vec<vec<bool>> sn(n, vec<bool>(m));
    // a.resize(n, vec<bool>(m));
    
    // calc

    // bt(0,0);
    // fori (i, 0, n*m) {
    //     cout << ct[i] << "\n";
    // }
    
    string s;
    foru (i, n) {
        cin >> s;
        // cout << s << endl;
        foru (j, m) {
            sn[i][j] = (s[j] == 'O');
        }
    }
    
    foru (i, n) {
        cin >> s;
        // cout << s << endl;
        foru (j, m) {
            t[i][j] = (s[j] == 'O');
        }
    }
    if (bit(n,m,t) != bit(n,m,sn)) {
        cout << "0\n";
        return 0;
    }
    
    ll ct = count(n, m, t);
    vec<ll> dp(9);
    fori (i, 1, ct) {
        dp[i] = calc(n, m, i) - dp[i-1];
        // cout << dp[i] << endl;
    }
    
    // cout << moves(n, m, t) << endl;
    cout << fixed << setprecision(15);
    cout << (long double)(2*moves(n,m,t)) / (long double)(dp[ct]) << endl;
    return 0;
}