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

// template {{{
#define  range(i, l, r) for (int i = (int)(l); i < (int)(r); (i) += 1)
#define rrange(i, l, r) for (int i = (int)(r) - 1; i >= (int)(l); (i) -= 1)

#define  whole(f, x, ...) ([&](decltype((x)) container) { return (f)(  begin(container),  end(container), ## __VA_ARGS__); })(x)
#define rwhole(f, x, ...) ([&](decltype((x)) container) { return (f)( rbegin(container), rend(container), ## __VA_ARGS__); })(x)

#define debug(x) cerr << "(" << __LINE__ << ")" << #x << ": " << (x) << endl

using i32 = int;
using u32 = unsigned int;
using i64 = long long;
using u64 = unsigned long long;

// constexpr i32 mod   = 998244353;
constexpr i32 mod   = 1e9 + 7;
constexpr i32 inf   = 1001001001;
constexpr i64 infll = 1001001001001001001ll;

constexpr int dx[] = {0, -1, 1, 0, -1, 1, -1, 1};
constexpr int dy[] = {-1, 0, 0, 1, -1, -1, 1, 1};

struct IoSetup { IoSetup(int x = 15){ cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(x); cerr << fixed << setprecision(x); } } iosetup;

template <typename T = i64> T input() { T x; cin >> x; return x; }

template <typename T> ostream &operator<<(ostream &os, vector<T> &v) { range(i, 0, v.size()) { os << v[i] << (i + 1 != v.size() ? " " : ""); } return os; }
template <typename T> istream &operator>>(istream &is, vector<T> &v) { for (T &in : v) is >> in; return is; }

template <typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
template <typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { is >> p.first >> p.second; return is; }

template <typename T> vector<T> make_vector(size_t a, T b) { return vector<T>(a, b); }
template <typename... Ts> auto make_vector(size_t a, Ts... ts) { return vector<decltype(make_vector(ts...))>(a, make_vector(ts...)); }

template <typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template <typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
// }}}

void solver() {
    int n = input(), m = input();

    auto ss = make_vector(n, m, '.');
    for (auto &s: ss) for (auto &c: s) cin >> c;

    int S = 2 * n * m;
    int T = 2 * n * m + 1;
    mcf_graph< i64, i64 > G(2 * n * m + 2);

    auto to_idx = [m](int i, int j) {
        return i * m + j;
    };

    range(i, 0, n) range(j, 0, m) {
        if (ss[i][j] == 'o') {
            G.add_edge(S, to_idx(i, j), 1, 0);
        }

        G.add_edge(to_idx(i, j) + n * m, T, 1, 0);
    }

    auto add_edge = [&](int y, int x) {
        int u = to_idx(y, x);

        auto ds = make_vector(n, m, inf);
        ds[y][x] = 0;
        queue< pair< int, int > > que;
        que.emplace(y, x);

        vector< bool > used(n * m, false);

        while (!que.empty()) {
            int i, j;
            tie(i, j) = que.front();
            que.pop();

            if (used[to_idx(i, j)]) continue;
            used[to_idx(i, j)] = true;

            int v = to_idx(i, j) + n * m;
            i64 cost = inf - abs(y - i) - abs(x - j);
            G.add_edge(u, v, 1, cost);

            if (i + 1 < n && ss[i + 1][j] != '#') {
                que.emplace(i + 1, j);
            }
            if (j + 1 < m && ss[i][j + 1] != '#') {
                que.emplace(i, j + 1);
            }
        }

        range(i, 0, n) range(j, 0, m) {
            if (ss[i][j] != 'o') continue;
            if (ds[i][j] == inf) continue;
            int u = to_idx(i, j);
            int v = to_idx(y, x) + n * m;
            int cost = inf - ds[i][j];
            G.add_edge(u, v, 1, cost);
        }
    };

    range(i, 0, n) range(j, 0, m) {
        if (ss[i][j] != 'o') continue;
        add_edge(i, j);
    }

    auto f = G.flow(S, T);
    i64 ans = f.first * inf - f.second;
    cout << ans << endl;
}

signed main(int argc, char *argv[]) {
    solver();
}



Measured memory_bytes: 8884