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//Sylwia Sapkowska
#include <bits/stdc++.h>
using namespace std;

void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

#define int long long
const int oo = 1e18, oo2 = 1e9+7, K = 30;
const int mod = 998244353;
int n, m;
vector<int>X = {-1, 1, 0, 0};
vector<int>Y = {0, 0, -1, 1};


int ile(vector<vector<char>>a){
	int curr = 0;
	for (int i = 1; i<=n; i++){
		for (int j = 1; j<=m; j++){
			if (a[i][j] == 'O'){
				// debug(i, j);
				for (int k = 0; k<4; k++){
					pair<int, int>s = {i+X[k], j+Y[k]};
					if (s.first >= 1 && s.second >= 1 && s.first <= n && s.second <= m){
						if (a[s.first][s.second] == '.'){
							// debug(s);
							curr++;
						}
					}
				}
			}
		}
	}
	return curr;
}

void solve(){
	cin >> n >> m;
	int k = 0;
	int A0 = 0, A1 = 0, B0 = 0, B1 = 0;
	vector<vector<char>>a(n+1, vector<char>(m+1));
	vector<vector<char>>b(n+1, vector<char>(m+1));
	for (int i = 1; i<=n; i++){
		for (int j = 1; j<=m; j++){
			cin >> a[i][j];
			if (a[i][j] == 'O'){
				k++;
				if ((i+j)&1) A0++;
				else A1++;
			}
		}
	}
	string s; getline(cin, s);
	for (int i = 1; i <= n; i++){
		for (int j = 1; j<=m; j++){
			cin >> b[i][j];
			if (b[i][j] == 'O'){
				if ((i+j)&1) B0++;
				else B1++;
			}
		}
	}
	if ((A0-B0)%2 != 0 || (A1-B1)%2 != 0){
		cout << "0\n";
		return;
	}
	vector<vector<int>>c(n*m+2, vector<int>(n*m+2));
	c[0][0] = 1;
	for (int i = 1; i<=n*m; i++){
		c[i][i] = c[i][0] = 1;
		for (int j = 1; j<i; j++){
			c[i][j] = c[i-1][j] + c[i-1][j-1];
		}
	}
	int ans = c[n*m-2][k-1] * (n*(m-1) + m*(n-1));
	// debug(ile(b));
	cout << fixed << setprecision(15) << (long double)(ile(b))/ans << "\n";
}


int32_t main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);

	solve();
	
	return 0;
}