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#include <bits/stdc++.h>

using namespace std;

typedef unsigned uint;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ldbl;
typedef pair<int, int> pii;
typedef pair<uint, uint> puu;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<double, double> pdd;
typedef vector<int> vi;
typedef vector<uint> vu;
typedef vector<ll> vll;
typedef vector<ull> vull;
typedef vector<pii> vpii;
typedef vector<puu> vpuu;
typedef vector<pll> vpll;
typedef vector<pull> vpull;
typedef vector<string> vstr;
typedef vector<double> vdbl;
typedef vector<ldbl> vldbl;
#define pb push_back
#define ppb pop_back
#define pfr push_front
#define ppfr pop_front
#define emp emplace
#define empb emplace_back
#define be begin
#define rbe rbegin
#define all(x) (x).be(), (x).end()
#define rall(x) (x).rbe(), (x).rend()
#define fir first
#define sec second
#define mkp make_pair
#define brif(cond) if (cond) break
#define ctif(cond) if (cond) continue
#define retif(cond) if (cond) return
void canhazfast() {ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);}
template<typename T> T gcd(T a, T b) {return b ? gcd(b, a%b) : a;}
template<typename T> T extgcd(T a, T b, T &x, T &y)
{
    T x0 = 1, y0 = 0, x1 = 0, y1 = 1;
    while (b) {
        T q = a/b; a %= b; swap(a, b);
        x0 -= q*x1; swap(x0, x1);
        y0 -= q*y1; swap(y0, y1);
    }
    x = x0; y = y0; return a;
}
int ctz(uint x) {return __builtin_ctz(x);}
int ctzll(ull x) {return __builtin_ctzll(x);}
int clz(uint x) {return __builtin_clz(x);}
int clzll(ull x) {return __builtin_clzll(x);}
int popcnt(uint x) {return __builtin_popcount(x);}
int popcntll(ull x) {return __builtin_popcountll(x);}
int bsr(uint x) {return 31^clz(x);}
int bsrll(ull x) {return 63^clzll(x);}

#define NM 8
#define CNT 8
#define SZ (1<<NM)

int tmsk[NM];
char s[NM][NM+8], t[NM][NM+8];
int row_deg[SZ];
pull dp[NM][CNT+1][SZ][2]; /// row, cnt, msk, par -> deg(cnt, sum)

int row_par(int row, int msk)
{
    return popcnt((0xaa>>(row%2))&msk)%2;
}

void update(pull &dst, pull src, int deg)
{
    dst.fir += src.fir;
    dst.sec += src.sec+src.fir*deg;
}

int main()
{
    canhazfast();

    int n, m, sz, gmsk;
    int spar = 0, tpar = 0, stcnt = 0;
    ull tdeg, totcnt = 0, degsum = 0;

    cin >> n >> m;
    sz = 1<<m;
    gmsk = sz-1;
    for (int i = 0; i < n; ++i) {
        cin >> s[i];
        for (int j = 0; j < m; ++j) {
            if (s[i][j] == 'O') {
                ++stcnt;
                spar ^= (i^j)&1;
            }
        }
    }
    for (int i = 0; i < n; ++i) {
        cin >> t[i];
        for (int j = 0; j < m; ++j) {
            if (t[i][j] == 'O') {
                tmsk[i] |= 1<<j;
                tpar ^= (i^j)&1;
            }
        }
    }
    retif(spar != tpar) cout << "0\n", 0;

    for (int msk = 0; msk < sz; ++msk) row_deg[msk] = popcnt((msk^(msk>>1))&(gmsk>>1));
    tdeg = row_deg[tmsk[0]];
    for (int i = 1; i < n; ++i) {
        tdeg += row_deg[tmsk[i]];
        tdeg += popcnt(tmsk[i-1]^tmsk[i]);
    }

    //cerr << "init:\nmsk\tpcnt\tpar\tdeg\n";
    for (int msk = 0; msk < sz; ++msk) {
        int cnt = popcnt(msk);
        int par = row_par(0, msk);
        dp[0][cnt][msk][par] = {1, row_deg[msk]};
        //cerr << bitset<5>(msk) << '\t' << cnt << '\t' << par << '\t' << row_deg[msk] << '\n';
    }
    for (int i = 1; i < n; ++i) {
        for (int cur_cnt = 0; cur_cnt <= stcnt; ++cur_cnt) {
            for (int cur_msk = 0; cur_msk < sz; ++cur_msk) {
                int pre_cnt = cur_cnt-popcnt(cur_msk);
                ctif(pre_cnt < 0);
                int par_diff = row_par(i, cur_msk);
                int row_deg_diff = row_deg[cur_msk];
                for (int pre_msk = 0; pre_msk < sz; ++pre_msk) {
                    int deg_diff = popcnt(pre_msk^cur_msk)+row_deg_diff;
                    for (int par : {0, 1}) {
                        pull &dst = dp[i][cur_cnt][cur_msk][par];
                        pull src = dp[i-1][pre_cnt][pre_msk][par^par_diff];
                        update(dst, src, deg_diff);
                    }
                }
            }
        }
    }

    //cerr << "final row:\nmsk\tcnt\tsum\n";
    for (int msk = 0; msk < sz; ++msk) {
        pull p = dp[n-1][stcnt][msk][tpar];
        degsum += p.sec;
        //totcnt += p.fir;
        ///ctif(p.fir == 0);
        //cerr << msk << '\t' << p.fir << '\t' << p.sec << '\n';
    }
    //cerr << "tdeg = " << tdeg << '\n';
    //cerr << "totcnt = " << totcnt << '\n';
    //cerr << "degsum = " << degsum << '\n';
    cout << tdeg/degsum << '.';
    tdeg %= degsum;
    constexpr int prec = 15;
    for (int i = 0; i < prec; ++i) {
        tdeg *= 10;
        cout << char(tdeg/degsum+'0');
        tdeg %= degsum;
    }
    cout << '\n';

    return 0;
}