#pragma region include
#include <iostream>
#include <iomanip>
#include <stdio.h>
#include <vector>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
#include <string>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <limits>
#include <list>
#include <numeric>
#include <queue>
#include <stack>
#include <utility>
#include <array>
#include <random>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <assert.h>
using namespace std;
typedef long long ll;
#define dump(x) cerr << #x << " = " << (x) << " [" << __LINE__ << ":" << __FUNCTION__ << "] " << endl;
// vector出力
template < typename T >
ostream& operator<<(ostream& os, vector< T >& v) {
    os << "{";
    for (int i = 0; i < (int)v.size(); i++) {
        os << v[i] << (i < v.size() - 1 ? ", " : "");
    }
    os << "}";
    return os;
}
// pair出力
template < typename T, typename U >
ostream& operator<<(ostream& os, pair< T, U >& p) {
    return os << "(" << p.first << ", " << p.second << ")";
}
// map出力
template < typename T, typename U >
ostream& operator<<(ostream& os, map< T, U >& map_var) {
    os << "{";
    for (auto itr = map_var.begin(); itr != map_var.end(); itr++) {
        os << "(" << itr->first << ", " << itr->second << ")";
        itr++;
        if (itr != map_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}
// set 出力
template < typename T >
ostream& operator<<(ostream& os, set< T >& set_var) {
    os << "{";
    for (auto itr = set_var.begin(); itr != set_var.end(); itr++) {
        os << *itr;
        ++itr;
        if (itr != set_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}
#pragma endregion

/////////////////////////////////////////

// Cap : 容量, Cost : コスト
template <typename Cap, typename Cost>
struct MininumCostFlow {
private:
    struct _edge {
        int to, rev;
        Cap cap;
        Cost cost;
    };
    int _n; // サイズ
    std::vector<std::pair<int, int>> pos; // どこから出る辺の何番目(firstのsecond番目)
    std::vector<std::vector<_edge>> g;
public:
    MininumCostFlow() {}

    // n : グラフのサイズ
    MininumCostFlow(int n) : _n(n), g(n) {}

    // from から to に 容量 cap コスト cost の有向辺を張る 
    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;
    };

    // i 番目に追加された辺の状態
    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,
        };
    }

    // 全ての辺の状態
    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;
    }

    // s -> t の (最大流量, 最小コスト)
    std::pair<Cap, Cost> flow(int s, int t) {
        return flow(s, t, std::numeric_limits<Cap>::max());
    }

    // s -> t の flow_limit までの(最大流量, 最小コスト)
    std::pair<Cap, Cost> flow(int s, int t, Cap flow_limit) {
        return slope(s, t, flow_limit).back();
    }

    // s -> t の(流量,最小コスト)
    std::vector<std::pair<Cap, Cost>> slope(int s, int t) {
        return slope(s, t, std::numeric_limits<Cap>::max());
    }

    // s -> t の flow_limit までの(流量,最小コスト)
    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);
        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;
                for (int i = 0; i < int(g[v].size()); i++) {
                    auto e = g[v][i];
                    if (vis[e.to] || !e.cap) continue;
                    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] -= 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;
    }

    void print() {
        for(auto e : this->edges()) {
            cout << e.from << "->" << e.to << " [" << e.flow << "/" << e.cap << "], cost = " << e.cost << endl;
        }
    }
};

int main() {
    int n,m;cin >> n >> m;
    vector<string> s(n);
    MininumCostFlow<ll,ll> g(n*m+2);
    for (int i = 0; i < n; i++) {
        cin >> s[i];
        for (int j = 0; j < m; j++) {
            if (s[i][j] == 'o') {
                g.add_edge(n*m,i*m+j,1,0);
            }
            if (s[i][j] != '#') {
                g.add_edge(i*m+j,n*m+1,1,n+m-i-j);
            }
        }
    }
    int dx[] = {0,1}, dy[] = {1,0};
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            for(int k = 0; k < 2;k++) {
                int x = i + dx[k], y = j + dy[k];
                if (x >= n || y >= m || s[x][y] == '#') continue;
                g.add_edge(i*m+j,x*m+y,n*m,0);
            }
        }
    }
    g.flow(n*m,n*m+1);
    ll ans = 0;
    for (auto e : g.edges()) {
        if (e.from == n*m || e.to == n*m+1) continue;
        ans += e.flow;
    }
    //g.print();
    cout << ans << endl;
    return 0;
}

/////////////////////////////////////////

Measured memory_bytes: 4300