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#include <bits/stdc++.h>
#define dbg(x) " [" << #x << ": " << (x) << "] "
using namespace std;
template<typename A, typename B>
ostream& operator<<(ostream& out, const pair<A,B>& p) {
    return out << "(" << p.first << ", " << p.second << ")";
}
template<typename T>
ostream& operator<<(ostream& out, const vector<T>& c) {
    out << "{";
    for(auto it = c.begin(); it != c.end(); it++) {
        if(it != c.begin()) out << ", ";
        out << *it;
    }
    return out << "}";
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n,m;
    cin >> n >> m;
    vector<string> a(n), b(n);
    int cnt = 0;
    for(int i = 0; i < n; i++) {
        cin >> a[i];
        for(int j = 0; j < m; j++) {
            if(a[i][j] == 'O') cnt += (i & 1) == (j & 1);
        }
    }
    int count = 0;
    for(int i = 0; i < n; i++) {
        cin >> b[i];
        for(int j = 0; j < m; j++) {
            if(b[i][j] == 'O') {
                cnt -= (i & 1) == (j & 1);
                count++;
            }
        }
    }
    if(abs(cnt) & 1) {
        cout << 0 << endl;
        return 0;
    }
    const vector<int> dx = {0, 0, -1, 1};
    const vector<int> dy = {-1, 1, 0, 0};
    int deg = 0;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            if(b[i][j] == '.') continue;
            for(int k = 0; k < 4; k++) {
                if(i + dx[k] < 0 || i + dx[k] >= n || j + dy[k] < 0 || j + dy[k] >= m || b[i + dx[k]][j + dy[k]] == 'O') continue;
                deg++;
            }
        }
    }
    long long bin = 1;
    for(int i = 1; i <= count - 1; i++) {
        bin = bin * (n * m - 1 - i) / i;
    }
    cout << fixed << setprecision(18) << 1.0 * deg / (bin * (2 * n * m - n - m)) << endl;
    return 0;
}