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#include <vector>
#include <iostream>
#include <sstream>
#include <math.h>
#include <sys/time.h>
#include <cstdlib>
#include <algorithm>
#include <cassert>
#include <cstring>
#include <fstream>
#include <set>
#include <map>
#include <iomanip>
#include <queue>

#define FOR(i,a,b)  for(__typeof(b) i=(a);i<(b);++i)
#define REP(i,a)    FOR(i,0,a)
#define FOREACH(x,c)   for(__typeof(c.begin()) x=c.begin();x != c.end(); x++)
#define ALL(c)      c.begin(),c.end()
#define CLEAR(c)    memset(c,0,sizeof(c))
#define SIZE(c) (int) ((c).size())

#define PB          push_back
#define MP          make_pair
#define X           first
#define Y           second

#define ULL         unsigned long long
#define LL          long long
#define LD          long double
#define II         pair<int, int>
#define DD         pair<double, double>
#define FF          pair<float,float>

#define VC	    vector
#define VI          VC<int>
#define VVI         VC<VI>
#define VVVI        VC<VVI>
#define VD          VC<double>
#define VS          VC<string>
#define VII         VC<II>
#define VDD         VC<DD>
#define VFF         VC<FF>
#define VVD         VC<VD>
#define VVVD        VC<VVD>
#define VULL         VC<ULL>

#define DB(a)       cerr << #a << ": " << a << endl;

using namespace std;

template<class T> void print(VC < T > v) {cerr << "[";if (SIZE(v) != 0) cerr << v[0]; FOR(i, 1, SIZE(v)) cerr << "," << v[i]; cerr << "]\n";}
template<class T> string i2s(T &x) { ostringstream o; o << x; return o.str(); }
VS split(string &s, char c = ' ') {VS all; int p = 0, np; while (np = s.find(c, p), np >= 0) {all.PB(s.substr(p, np - p)); p = np + 1;} if (p < SIZE(s)) all.PB(s.substr(p)); return all;}

int N,M;
VS b1,b2;

int countMoves(VS b){
    int dx[4] = {-1,0,1,0};
    int dy[4] = {0,-1,0,1};
    int cnt = 0;
    REP(i,N) REP(j,M) if (b[i][j] == 'O'){
        REP(d,4){
            int x = i+dx[d];
            int y = j+dy[d];
            if (x >= 0 && x < N && y >= 0 && y < M && b[x][y] != 'O')
                cnt++;
        }
    }
    return cnt;
}

int countPawns(VS b){
    int cnt = 0;
    REP(i,N) REP(j,M) if (b[i][j] == 'O') cnt++;
    return cnt;
}

int main(int argc, char *argv[]){
    cin >> N >> M;
    string s;
    REP(i,N){
        cin >> s;
        b1.PB(s);
    }
    REP(i,N){
        cin >> s;
        b2.PB(s);
    }
    int p1 = 0;
    REP(i,N) REP(j,M) if (b1[i][j] == 'O') p1 += i+j;
    int p2 = 0;
    REP(i,N) REP(j,M) if (b2[i][j] == 'O') p2 += i+j;

    if (p1%2 != p2%2){
        cout << "0" << endl;
        return 0;
    }

    int cnt = countMoves(b2);
    int K = countPawns(b2);

    double ret = cnt;
    // divide by total moves which is [(N-1)*M+N*(M-1)]*(N*M-2 choose (K-1))
    REP(i,K-1) ret *= (i+1);
    ret /= (N-1)*M + N*(M-1);
    REP(i,K-1) ret /= N*M-2-i;
    cout << std::setprecision(15) << std::fixed;
    cout << ret << endl;
    return 0;
}