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#include<cstdio>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<string>
#include<vector>
#include<cmath>
#include<queue>
#include<unordered_map>
#include<bitset>

using namespace std;

typedef vector<int> VI;
typedef long long LL;
typedef vector<LL> VLL;
typedef pair<int, int> PII;
typedef vector<PII> VPII;

#define FOR(x, b, e) for(int x=b; x<=(e); ++x)
#define FORD(x, b, e) for(int x=b; x>=(e); --x)
#define REP(x, n) for(int x=0; x<(n); ++x)
#define VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define PB push_back
#define ST first
#define ND second

int n, m;

LL convert(vector<string> &s) {
    LL res = 0;
    REP(i, s.size()) {
        REP(j, s[i].size()) {
            if (s[i][j] == 'O') {
                res |= (1 << (i * n + j));
            }
        }
    }
    return res;
}

bool isSet(LL &p, int i) {
    return (p & (1 << i)) > 0;
}

LL set(LL p, int i) {
    return p | (1 << i);
}

LL unset(LL p, int i) {
    return p & ~(1 << i);
}

VLL next(LL p) {
    VLL moves;
    REP(x, n * m) {
        if (isSet(p, x)) {
            if (x % m > 0 && !isSet(p, x - 1)) moves.PB(set(unset(p, x), x - 1));
            if ((x + 1) % m > 0 && !isSet(p, x + 1)) moves.PB(set(unset(p, x), x + 1));
            if (x >= m && !isSet(p, x - m)) moves.PB(set(unset(p, x), x - m));
            if (x + m < n * m && !isSet(p, x + m)) moves.PB(set(unset(p, x), x + m));
        }
    }
    return moves;
}

int main() {
	ios_base::sync_with_stdio(0);
    cin.tie(NULL); cout.tie(NULL);
    cin >> n >> m; 
    vector<string> s_start(n), s_end(n);
    REP(i, n) cin >> s_start[i];
    REP(i, n) cin >> s_end[i];
    LL start = convert(s_start);
    LL end = convert(s_end);
    unordered_map<LL, int> states;
    queue<LL> q;
    states[start] = 0;
    q.push(start);
    LL sum = 0;
    while (!q.empty()) {
        LL c = q.front();
        //cout << "start from: " << bitset<9>(c) << '\n';
        q.pop();
        for (LL first : next(c)) {
            for (LL p : next(first)) {
                if (states.find(p) == states.end()) q.push(p);
                states[p]++;
                //cout << bitset<9>(p) << '\n';
                sum++;
            }
        }
    }
    cout << fixed << setprecision(15) << ((long double) states[end]) / sum << '\n';
    return 0;
}