#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;

#define int long long
#define rep(i, n) for (int i = 0; i < (int) (n); i++)
#define reps(i, n) for (int i = 1; i <= (int) (n); i++)
#define all(x) (x).begin(), (x).end()
#define uniq(x) (x).erase(unique(all(x)), (x).end())
#define bit(n) (1LL << (n))
#define dump(x) cerr << #x " = " << (x) << endl
using vint = vector<int>;
using vvint = vector<vint>;
using pint = pair<int, int>;
using vpint = vector<pint>;
template<typename T> using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>;
constexpr double PI = 3.1415926535897932384626433832795028;
constexpr int DY[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0};
constexpr int DX[9] = {1, 0, -1, 0, 1, -1, -1, 1, 0};
int sign(int x) { return (x > 0) - (x < 0); }
int gcd(int a, int b) {
    while (b) { swap(a %= b, b); }
    return a;
}
int lcm(int a, int b) { return a / gcd(a, b) * b; }
int cdiv(int a, int b) { return (a - 1 + b) / b; }
template<typename T> void fin(T mes) {
    cout << mes << endl;
    exit(0);
}
template<typename T> T sq(T x) { return x * x; }
template<typename T, typename U> bool chmax(T &a, const U &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U> bool chmin(T &a, const U &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U> ostream &operator<<(ostream &os, const pair<T, U> &rhs) {
    os << "(" << rhs.first << ", " << rhs.second << ")";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const vector<T> &rhs) {
    os << "{";
    for (auto itr = rhs.begin(); itr != rhs.end(); itr++) {
        os << *itr << (next(itr) != rhs.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const deque<T> &rhs) {
    os << "{";
    for (auto itr = rhs.begin(); itr != rhs.end(); itr++) {
        os << *itr << (next(itr) != rhs.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const set<T> &rhs) {
    os << "{";
    for (auto itr = rhs.begin(); itr != rhs.end(); itr++) {
        os << *itr << (next(itr) != rhs.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &rhs) {
    os << "{";
    for (auto itr = rhs.begin(); itr != rhs.end(); itr++) {
        os << *itr << (next(itr) != rhs.end() ? ", " : "");
    }
    os << "}";
    return os;
}
template<typename T, typename U> ostream &operator<<(ostream &os, const map<T, U> &rhs) {
    os << "{";
    for (auto itr = rhs.begin(); itr != rhs.end(); itr++) {
        os << *itr << (next(itr) != rhs.end() ? ", " : "");
    }
    os << "}";
    return os;
}
struct setup {
    static constexpr int PREC = 20;
    setup() {
        cout << fixed << setprecision(PREC);
        cerr << fixed << setprecision(PREC);
    };
} setup;

signed main() {
    int N, M;
    cin >> N >> M;
    vector<string> S(N);
    vint y, x;
    rep(i, N) {
        cin >> S[i];
        rep(j, M) { if (S[i][j] == 'o') { y.emplace_back(i), x.emplace_back(j); }}
    }
    int K = y.size();
    mcf_graph<int, int> graph(K + N * M + 2);
    int s = K + N * M, t = K + N * M + 1;
    rep(i, K) { graph.add_edge(s, i, 1, 0); }
    rep(i, N * M) { graph.add_edge(i + K, t, 1, 0); }
    int big = 1e11;
    rep(i, K) {
        vector<pint> cand;
        vector used(N, vector<bool>(M));
        auto dfs = [&](auto &&dfs, int cy, int cx) -> void {
            used[cy][cx] = true;
            cand.emplace_back(abs(cy - y[i]) + abs(cx - x[i]), cy * M + cx + K);
            rep(k, 2) {
                int ny = cy + DY[k], nx = cx + DX[k];
                if (ny < 0 || ny >= N || nx < 0 || nx >= M || S[ny][nx] == '#' || used[ny][nx]) { continue; }
                dfs(dfs, ny, nx);
            }
        };
        dfs(dfs, y[i], x[i]);
        sort(all(cand)), reverse(all(cand));
        rep(j, min((int) cand.size(), K)) {
            graph.add_edge(i, cand[j].second, 1, big - cand[j].first);
        }
    }
    cout << big * K - graph.flow(s, t).second << endl;
}

Measured memory_bytes: 4680