/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author aryssoncf
 */



// Taken from: https://github.com/bqi343/USACO/blob/master/Implementations/content/contest/templateShort.cpp

#include <utility>
#include <vector>
#include <random>
#include <chrono>
#include <cassert>
#include <set>
#include <queue>
#include <map>
#include <numeric>
#include <algorithm>
#include <iostream>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <complex>
#include <stack>
#include <array>
#include <unordered_set>
#include <climits>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int, int> pii;

typedef vector<int> vi;
typedef vector<ull> vul;
typedef vector<ll> vl;
typedef vector<pii> vpii;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rsz resize

#define mp make_pair
#define pb push_back
#define f first
#define s second

const int MOD = 1e9+7; // 998244353; // = (119<<23)+1
const int MX = 2e5+5;

template<class T> bool ckmin(T& a, const T& b) {
    return a > b ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) {
    return a < b ? a = b, 1 : 0; }

mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());


//
// Created by aryssoncf on 28/10/2019.
//

#include <type_traits>


#include <iterator>


template <typename T>
constexpr auto hasBegin(int) -> decltype(std::begin(std::declval<T>()), true) {
    return true;
}

constexpr bool hasBegin(...) {
    return false;
}

template <typename T>
using IsContainer = std::integral_constant<bool, hasBegin<T>(0)>;


#ifndef JHELPER_EXAMPLE_PROJECT_IO_HPP
#define JHELPER_EXAMPLE_PROJECT_IO_HPP

#endif //JHELPER_EXAMPLE_PROJECT_IO_HPP

template<typename T>
std::istream &operator>>(std::istream &is, std::vector<T> &vec) {
    for (T &element: vec) {
        is >> element;
    }
    return is;
}

template<typename T, typename U>
std::istream &operator>>(std::istream &is, std::pair<T, U> &p) {
    is >> p.first;
    is >> p.second;
    return is;
}

template <class X, class Y>
std::ostream & operator << (std::ostream & os, std::pair <X, Y> const& p) {
    return os << p.first << " " << p.second;
}

template <class Ch, class Tr, class Container>
std::basic_ostream <Ch, Tr> & operator << (std::basic_ostream <Ch, Tr>& os, Container const& x) {
    bool first = true;
    for(auto& y : x) {
        if (first) {
            first = false;
        } else {
            os << " ";
        }
        os << y;
    }
    return os;
}








using namespace std;

template <typename T>
class VectorVectorBaseGraph {
public:
    using Edge = T;
    using Vertex = std::size_t;

    explicit VectorVectorBaseGraph(std::size_t n=0): g(n) {
    }

    template <typename U>
    using Collection = std::vector<U>;

    template <typename U>
    Collection<U> getCollection(const U& defaultValue) const {
        return Collection<U>(g.size(), defaultValue);
    }

    std::vector<std::size_t> vertices() const {
        std::vector<std::size_t> order(g.size());
        std::iota(order.begin(), order.end(), 0);
        return order;
    }

    const std::vector<Edge>& outgoingEdges(Vertex vertex) const {
        return g[vertex];
    }

    vector<Vertex> toposort() {
        int n = g.size();
        vector<bool> used(n);
        vector<Vertex> order;
        for (int i = 0; i < n; i++)
            if (!used[i])
                dfs(used, order, i);
        reverse(order.begin(), order.end());
        return order;
    }

    virtual Vertex endOfEdge(Vertex, Edge) const = 0;

protected:
    std::vector<std::vector<Edge>> g;

private:
    void dfs(vector<bool> &used, vector<Vertex> &order, int u) {
        used[u] = true;
        for (Edge ed : outgoingEdges(u)) {
            Vertex v = endOfEdge(u, ed);
            if (!used[v])
                dfs(used, order, v);
        }
        order.push_back(u);
    }
};


class SimpleGraph: public VectorVectorBaseGraph<std::size_t> {
public:
    explicit SimpleGraph(std::size_t n=0): VectorVectorBaseGraph(n) {}

    Vertex endOfEdge(Vertex, Edge edge) const {
        return edge;
    }

    void addEdge(Vertex from, Vertex to) {
        g[from].push_back(to);
    }
};

#ifndef ATCODER_MINCOSTFLOW_HPP
#define ATCODER_MINCOSTFLOW_HPP 1



#include <limits>



namespace atcoder {

template <class Cap, class Cost> struct mcf_graph {
  public:
    mcf_graph() {}
    mcf_graph(int n) : _n(n), g(n) {}

    int add_edge(int from, int to, Cap cap, Cost cost) {
        assert(0 <= from && from < _n);
        assert(0 <= to && to < _n);
        int m = int(pos.size());
        pos.push_back({from, int(g[from].size())});
        g[from].push_back(_edge{to, int(g[to].size()), cap, cost});
        g[to].push_back(_edge{from, int(g[from].size()) - 1, 0, -cost});
        return m;
    }

    struct edge {
        int from, to;
        Cap cap, flow;
        Cost cost;
    };

    edge get_edge(int i) {
        int m = int(pos.size());
        assert(0 <= i && i < m);
        auto _e = g[pos[i].first][pos[i].second];
        auto _re = g[_e.to][_e.rev];
        return edge{
            pos[i].first, _e.to, _e.cap + _re.cap, _re.cap, _e.cost,
        };
    }
    std::vector<edge> edges() {
        int m = int(pos.size());
        std::vector<edge> result(m);
        for (int i = 0; i < m; i++) {
            result[i] = get_edge(i);
        }
        return result;
    }

    std::pair<Cap, Cost> flow(int s, int t) {
        return flow(s, t, std::numeric_limits<Cap>::max());
    }
    std::pair<Cap, Cost> flow(int s, int t, Cap flow_limit) {
        return slope(s, t, flow_limit).back();
    }
    std::vector<std::pair<Cap, Cost>> slope(int s, int t) {
        return slope(s, t, std::numeric_limits<Cap>::max());
    }
    std::vector<std::pair<Cap, Cost>> slope(int s, int t, Cap flow_limit) {
        assert(0 <= s && s < _n);
        assert(0 <= t && t < _n);
        assert(s != t);
        // variants (C = maxcost):
        // -(n-1)C <= dual[s] <= dual[i] <= dual[t] = 0
        // reduced cost (= e.cost + dual[e.from] - dual[e.to]) >= 0 for all edge
        std::vector<Cost> dual(_n, 0), dist(_n);
        std::vector<int> pv(_n), pe(_n);
        std::vector<bool> vis(_n);
        auto dual_ref = [&]() {
            std::fill(dist.begin(), dist.end(),
                      std::numeric_limits<Cost>::max());
            std::fill(pv.begin(), pv.end(), -1);
            std::fill(pe.begin(), pe.end(), -1);
            std::fill(vis.begin(), vis.end(), false);
            struct Q {
                Cost key;
                int to;
                bool operator<(Q r) const { return key > r.key; }
            };
            std::priority_queue<Q> que;
            dist[s] = 0;
            que.push(Q{0, s});
            while (!que.empty()) {
                int v = que.top().to;
                que.pop();
                if (vis[v]) continue;
                vis[v] = true;
                if (v == t) break;
                // dist[v] = shortest(s, v) + dual[s] - dual[v]
                // dist[v] >= 0 (all reduced cost are positive)
                // dist[v] <= (n-1)C
                for (int i = 0; i < int(g[v].size()); i++) {
                    auto e = g[v][i];
                    if (vis[e.to] || !e.cap) continue;
                    // |-dual[e.to] + dual[v]| <= (n-1)C
                    // cost <= C - -(n-1)C + 0 = nC
                    Cost cost = e.cost - dual[e.to] + dual[v];
                    if (dist[e.to] - dist[v] > cost) {
                        dist[e.to] = dist[v] + cost;
                        pv[e.to] = v;
                        pe[e.to] = i;
                        que.push(Q{dist[e.to], e.to});
                    }
                }
            }
            if (!vis[t]) {
                return false;
            }

            for (int v = 0; v < _n; v++) {
                if (!vis[v]) continue;
                // dual[v] = dual[v] - dist[t] + dist[v]
                //         = dual[v] - (shortest(s, t) + dual[s] - dual[t]) + (shortest(s, v) + dual[s] - dual[v])
                //         = - shortest(s, t) + dual[t] + shortest(s, v)
                //         = shortest(s, v) - shortest(s, t) >= 0 - (n-1)C
                dual[v] -= dist[t] - dist[v];
            }
            return true;
        };
        Cap flow = 0;
        Cost cost = 0, prev_cost = -1;
        std::vector<std::pair<Cap, Cost>> result;
        result.push_back({flow, cost});
        while (flow < flow_limit) {
            if (!dual_ref()) break;
            Cap c = flow_limit - flow;
            for (int v = t; v != s; v = pv[v]) {
                c = std::min(c, g[pv[v]][pe[v]].cap);
            }
            for (int v = t; v != s; v = pv[v]) {
                auto& e = g[pv[v]][pe[v]];
                e.cap -= c;
                g[v][e.rev].cap += c;
            }
            Cost d = -dual[s];
            flow += c;
            cost += c * d;
            if (prev_cost == d) {
                result.pop_back();
            }
            result.push_back({flow, cost});
            prev_cost = cost;
        }
        return result;
    }

  private:
    int _n;

    struct _edge {
        int to, rev;
        Cap cap;
        Cost cost;
    };

    std::vector<std::pair<int, int>> pos;
    std::vector<std::vector<_edge>> g;
};

}  // namespace atcoder

#endif  // ATCODER_MINCOSTFLOW_HPP





template <typename Graph>
std::vector<int> bfsDistances(const Graph& graph, const typename Graph::Vertex& from) {
    auto result = graph.getCollection(-1);
    std::queue<typename Graph::Vertex> q;
    q.push(from);
    result[from] = 0;
    while (!q.empty()) {
        const auto& v = q.front();
        for (const auto& e: graph.outgoingEdges(v)) {
            const auto& to = graph.endOfEdge(v, e);
            if (result[to] == -1) {
                result[to] = result[v] + 1;
                q.push(to);
            }
        }
        q.pop();
    }
    return result;
}


using namespace std;

class CMovingPieces {

    static const int MAX = 100;

public:
	void solve(std::istream& in, std::ostream& out) {
        int n, m;
        in >> n >> m;
        vector<str> grid(n);
        in >> grid;
        SimpleGraph graph(n * m);
        FOR(i, 0, n) {
            FOR(j, 0, m) {
                if (grid[i][j] != '#') {
                    int u = i * m + j;
                    if (i + 1 < n and grid[i + 1][j] != '#') {
                        int v = (i + 1) * m + j;
                        graph.addEdge(u, v);
                    }
                    if (j + 1 < m and grid[i][j + 1] != '#') {
                        int v = i * m + j + 1;
                        graph.addEdge(u, v);
                    }
                }
            }
        }
        int source = 2 * n * m, sink = source + 1, N = sink + 1;
        atcoder::mcf_graph<int, int> mcf(N);
        FOR(i, 0, n) {
            FOR(j, 0, m) {
                mcf.add_edge((n + i) * m + j, sink, 1, 0);
                if (grid[i][j] == 'o') {
                    int u = i * m + j;
                    mcf.add_edge(source, u, 1, 0);
                    vi dists = bfsDistances(graph, u);
                    FOR(v, 0, n * m) {
                        if (dists[v] != -1) {
                            mcf.add_edge(u, n * m + v, INT_MAX, MAX - dists[v]);
                        }
                    }
                }
            }
        }
        auto result = mcf.flow(source, sink);
        int res = result.f * MAX - result.s;
        out << res << '\n';
	}

	void setup() {}
};


int main() {
    std::ios_base::sync_with_stdio(false);
	CMovingPieces solver;
    solver.setup();
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	in.tie(nullptr);
    out << std::fixed;
    out.precision(20);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 7396