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#include <stdio.h>
#include <time.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <map> 
#include <string>
#include <vector>  
#include <iostream> 
#include <sstream> 
#include <queue>
#include <algorithm>
#include <assert.h>
#include <iomanip> 


using namespace std;

#define ll long long
#define PB 		push_back
#define FOR(a,start,end) 	for(int a=int(start); a<int(end); a++)
#define INF 		INT_MAX
#define SORT(a) 	sort(a.begin(),a.end()) 
#define CL(a,x) 		memset(a,x,sizeof(a))
#define REP(a,x)	for(int a=0;a<x;a++)
#define REP1(a,x)	for(int a=1;a<=x;a++)
#define MP 		make_pair



typedef vector<ll>     vi;
typedef pair<ll, ll>     pii;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<vector<ll> > vvi;
typedef vector<vector<string> > vvs;
typedef vector<pair<string, string> > vss;
typedef pair<string, string> pss;
typedef pair<ll, pii> ppii;
typedef vector<ppii> vppii;
typedef vector<vector<pii> > vvii;
typedef vector<vvi> vvvi;


ll  n, k, q, d, r, g, b, z, p, a, c, m, k1, k2;
char zn;
vs vw, vwk;
string wa, wb;
vi vk, va, vk1, vk2;
vii vkx,vkx2;
vvi vvz;
vector<double> vax, vax2;
vector<vector<double> > vvax, vvbx;
map<int, int> hz,hz2,hz0;
class Stan;
vector<Stan *> vgs;

class Stan {
	vii vkx;
	int zob;
	double px;
	double px_new;
	bool emp(pii p0) {
		for (int i = 0; i < (int)vkx.size(); i++) {
			if (vkx[i] == p0)
				return false;
		}
		return true;
	}
	vii gil(pii p0) {
		vii vaw;
		vaw.clear();
		if ((p0.first > 0) && (emp(MP(p0.first - 1, p0.second)))) {
			vaw.push_back(MP(p0.first - 1, p0.second));
		}
		if ((p0.first <n-1) && (emp(MP(p0.first + 1, p0.second)))) {
			vaw.push_back(MP(p0.first + 1, p0.second));
		}
		if ((p0.second > 0) && (emp(MP(p0.first, p0.second-1)))) {
			vaw.push_back(MP(p0.first, p0.second-1));
		}
		if ((p0.second < m-1) && (emp(MP(p0.first, p0.second + 1)))) {
			vaw.push_back(MP(p0.first, p0.second+1));
		}
		return vaw;
	}
	int checka() {
		int da = 0;
		for (int i = 0; i < vkx.size(); i++) {
			if ((int)gil(vkx[i]).size() == 0)
				da++;
		}
		return da;
	}
	double getPxNew() {
		return px_new;
	}
public:
	Stan(vii vpx,double px0) {
		vkx = vpx;
		px_new = px0;
		px = 0.0;
		zob = 0;
		for (int i = 0; i < (int)vkx.size(); i++) {
			zob ^= vvz[vkx[i].first][vkx[i].second];
		}
	}
	Stan(vii vpx, double px0,int zobn) {
		vkx = vpx;
		px_new = px0;
		px = 0.0;
		zob = zobn;
		
	}
	void addP(double px0) {
		px_new += px0;
	}
	void getNext() {
		
		int da = checka();
		a -= da;
		for (int i = 0; i < (int)vkx.size(); i++) {
			vii vaw = gil(vkx[i]);
			int aw = (int)vaw.size();
			for (int j = 0; j < (int)vaw.size(); j++) {
				
				int nzob = zob ^ vvz[vkx[i].first][vkx[i].second];
				nzob^= vvz[vaw[j].first][vaw[j].second];
				map<int,int>::iterator it = hz0.find(nzob);

				if (it != hz0.end()) {
					if (vgs[hz0[nzob]]->getPxNew() == 0.0)
						vk2.push_back(hz0[nzob]);
					vgs[hz0[nzob]]->addP((px / a) / aw);
				}
				else {

					pii p1 = vkx[i];
					vkx[i] = vaw[j];
					Stan* nst = new Stan(vkx, (px / a) / aw,nzob);
					vgs.push_back(nst);
					hz0[nzob] = (int)vgs.size()-1;
					vkx[i] = p1;
					vk2.push_back((int)vgs.size() - 1);
				}
				
			}
		}
		a += da;
	}
	int getZob() {
		return zob;
	}
	
	void updP() {
		px = px_new;
		px_new = 0.0;
	}
	double getP() {
		return px;
	}

};
Stan* st;
Stan* stk;


int main() {
	//freopen("c:\\wojtek\\uva\\pa\\debug\\3.in", "rt", stdin);
	//d = 1000000007;
	srand(79);
	//while (1) {

	cin >> n >> m;

	vk.assign(m, 0);
	vvz.assign(n, vk);
	vkx.clear();
	vkx2.clear();
	wa.assign(m, '.');
	vw.assign(n, wa);
	vwk.assign(n, wa);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			vvz[i][j] = rand();
		}
	}
	a = 0;
	for (int i = 0; i < n; i++) {
		cin >> vw[i];
	}
	for (int i = 0; i < n; i++) {
		cin >> vwk[i];
	}
	k1 = 0;
	k2 = 0;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			if (vw[i][j] == 'O') {
				k1 += i + j;
				vkx.push_back(MP(i, j));
			}
			if (vwk[i][j] == 'O') {
				k2 += i + j;
				vkx2.push_back(MP(i, j));
			}
		}
	}
	if ((k1 % 2) != (k2 % 2)) {
		cout << 0 << endl;
		return 0;
	}

	//	while (1) {
	//		cin >> k;
	k = 1000;
	st = new Stan(vkx,1.0);
vgs.clear();
	vgs.push_back(st);
	hz0.clear();
	hz0[st->getZob()] = 0;
	bool ts = true;
	for (int i = 0; i < (int)vkx.size(); i++) {
		if (vkx[i] != vkx2[i]) {
			ts = false;
			break;
		}
	}
	if (!ts) {
		stk = new Stan(vkx2, 0.0);
		hz0[stk->getZob()] = 1;
			vgs.push_back(stk);
	}
	
	a = 0;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			if (vw[i][j] == 'O') {
				//vvax[i][j] = 1.0;
				a++;
			}
		}
	}
	vk1.clear();
	vk2.clear();
	vk1.push_back(0);
	vgs[0]->updP();
	for (int cas = 0; cas < k; cas++) {

		for (int ix = 0; ix < (int)vk1.size(); ix++) {
			vgs[vk1[ix]]->getNext();
		}
		for (int i = 0; i < (int)vk2.size(); i++)
			vgs[vk2[i]]->updP();
		for (int i = 0; i < (int)vk1.size(); i++)
			vgs[vk1[i]]->updP();
		vk1.swap(vk2);
		vk2.clear();
	}
	double zx;
	if (!ts)
		zx = vgs[1]->getP();
	else
		zx = vgs[0]->getP();
	
	cout << setprecision(15) << zx << endl;
	//}
// }

	return 0;

}