// Author: Tyler Wang

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstdint>
#include <cstdlib>
#include <deque>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <string_view>
#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>

using namespace std;

template <class C>
constexpr auto ssize(const C& c)
    -> std::common_type_t<std::ptrdiff_t,
                          std::make_signed_t<decltype(c.size())>> {
  using R = std::common_type_t<std::ptrdiff_t,
                               std::make_signed_t<decltype(c.size())>>;
  return (R)c.size();
}

template <class T, std::ptrdiff_t N>
constexpr std::ptrdiff_t ssize(const T (&)[N]) noexcept {
  return N;
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, bool> has_single_bit(
    T x) noexcept {
  return x != 0 && (x & (x - 1)) == 0;
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, int> countl_zero(
    T x) noexcept {
  if constexpr (sizeof(T) <= sizeof(unsigned)) {
    return __builtin_clz(x) - (std::numeric_limits<unsigned>::digits -
                               std::numeric_limits<T>::digits);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long)) {
    return __builtin_clzl(x) - (std::numeric_limits<unsigned long>::digits -
                                std::numeric_limits<T>::digits);
  } else {
    static_assert(sizeof(T) <= sizeof(unsigned long long));
    return __builtin_clzll(x) -
           (std::numeric_limits<unsigned long long>::digits -
            std::numeric_limits<T>::digits);
  }
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, int> countr_zero(
    T x) noexcept {
  if constexpr (sizeof(T) <= sizeof(unsigned)) {
    return __builtin_ctz(x);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long)) {
    return __builtin_ctzl(x);
  } else {
    static_assert(sizeof(T) <= sizeof(unsigned long long));
    return __builtin_ctzll(x);
  }
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, int> popcount(T x) noexcept {
  if constexpr (sizeof(T) <= sizeof(unsigned)) {
    return __builtin_popcount(x);
  } else if constexpr (sizeof(T) <= sizeof(unsigned long long)) {
    return __builtin_popcountl(x);
  } else {
    static_assert(sizeof(T) <= sizeof(unsigned long long));
    return __builtin_popcountll(x);
  }
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, T> bit_width(T x) noexcept {
  return (T)(std::numeric_limits<T>::digits - countl_zero(x));
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, T> bit_ceil(T x) noexcept {
  return (T)(x <= 1 ? 1 : (T)1 << bit_width((T)(x - 1)));
}

template <typename T>
constexpr std::enable_if_t<std::is_unsigned_v<T>, T> bit_floor(T x) noexcept {
  return (T)(x == 0 ? 0 : (T)1 << (bit_width(x) - 1));
}

template <typename Fun>
class y_combinator_result {
 public:
  template <typename T>
  explicit y_combinator_result(T&& fun) : fun_(std::forward<T>(fun)) {}

  template <typename... Args>
  decltype(auto) operator()(Args&&... args) {
    return fun_(std::ref(*this), std::forward<Args>(args)...);
  }

 private:
  Fun fun_;
};

template <typename Fun>
decltype(auto) y_combinator(Fun&& fun) {
  return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}

template <typename T>
std::ostream& operator<<(std::ostream& os, const std::optional<T>& opt);

template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::pair<T1, T2>& p);

template <typename... Ts>
std::ostream& operator<<(std::ostream& os, const std::tuple<Ts...>& t);

template <typename Container,
          std::enable_if_t<!std::is_convertible_v<Container, std::string_view>,
                           typename Container::const_iterator>* = nullptr>
std::ostream& operator<<(std::ostream& os, const Container& c);

template <typename ContainerAdaptor,
          typename ContainerAdaptor::container_type* = nullptr>
std::ostream& operator<<(std::ostream& os, const ContainerAdaptor& a);

template <typename T>
std::ostream& operator<<(std::ostream& os, const std::optional<T>& opt) {
  return opt ? os << *opt : os << "nullopt";
}

template <typename T1, typename T2>
std::ostream& operator<<(std::ostream& os, const std::pair<T1, T2>& p) {
  return os << '{' << p.first << ", " << p.second << '}';
}

template <typename... Ts>
std::ostream& operator<<(std::ostream& os, const std::tuple<Ts...>& t) {
  return std::apply(
      [&os](const Ts&... args) -> std::ostream& {
        os << '{';
        int i = 0;
        ((os << (i++ == 0 ? "" : ", ") << args), ...);
        return os << '}';
      },
      t);
}

template <typename Container,
          std::enable_if_t<!std::is_convertible_v<Container, std::string_view>,
                           typename Container::const_iterator>*>
std::ostream& operator<<(std::ostream& os, const Container& c) {
  os << '{';
  for (auto it = c.begin(); it != c.end(); ++it) {
    os << (it == c.begin() ? "" : ", ") << *it;
  }
  return os << '}';
}

template <typename ContainerAdaptor, typename ContainerAdaptor::container_type*>
std::ostream& operator<<(std::ostream& os, const ContainerAdaptor& a) {
  class subadaptor : public ContainerAdaptor {
   public:
    const auto& c() const { return ContainerAdaptor::c; }
  };
  return os << static_cast<const subadaptor&>(a).c();
}

namespace detail {

template <typename... Ts>
void print(std::ostream& os, int line, std::string_view keys,
           const Ts&... vals) {
  if constexpr (sizeof...(Ts) == 0) {
    os << "  " << line << " |" << std::endl;
  } else {
    std::vector<std::string_view> key_list;
    key_list.reserve(sizeof...(Ts));
    int first = 0, paren = 0;
    for (int i = 0; i < (int)keys.size(); ++i) {
      switch (keys[i]) {
        case '(':
        case '[':
        case '{':
          ++paren;
          break;
        case ')':
        case ']':
        case '}':
          --paren;
          break;
        case ',':
          if (paren == 0) {
            key_list.push_back(keys.substr(first, i - first));
            first = i;
          }
          break;
      }
    }
    key_list.push_back(keys.substr(first));
    assert(key_list.size() == sizeof...(Ts));
    os << "  " << line << " | ";
    int i = 0;
    ((os << key_list[i++] << " = " << vals), ...);
    os << std::endl;
  }
}

}  // namespace detail

#if defined(TYLER) && defined(__clang__)
#define debug(...) \
  detail::print(std::cerr, __LINE__, #__VA_ARGS__, ##__VA_ARGS__)
#elif defined(TYLER) && defined(__GNUC__)
#define debug(...) \
  detail::print(std::cerr, __LINE__, #__VA_ARGS__ __VA_OPT__(, ) __VA_ARGS__)
#else
#define debug(...) ((void)0)
#endif

template <typename Flow, typename Cost>
class min_cost_flow {
 public:
  min_cost_flow(int n) : graph_(n) {}

  void add_edge(int from, int to, Flow cap, Cost cost) {
    graph_[from].emplace_back(to, (int)graph_[to].size(), cap, cost);
    graph_[to].emplace_back(from, (int)graph_[from].size() - 1, 0, -cost);
    m_ += 2;
  }

  std::pair<Flow, Cost> solve(
      int source, int sink, Flow max_flow = std::numeric_limits<Flow>::max()) {
    std::vector<Cost> costs;
    costs.reserve(m_);
    for (std::vector<edge>& edges : graph_) {
      for (edge& e : edges) {
        e.flow = 0;
        costs.push_back(e.cost);
      }
    }
    int n = (int)graph_.size();
    std::vector<Cost> dist(n, INF_COST);
    dist[source] = 0;
    std::vector<std::pair<int, edge*>> pred(n);
    std::queue<int> q;
    q.push(source);
    std::vector<bool> active(n, false);
    active[source] = true;
    while (!q.empty()) {  // Bellman-Ford shortest paths
      int u = q.front();
      q.pop();
      active[u] = false;
      for (edge& e : graph_[u]) {
        if (e.flow < e.cap && dist[u] + e.cost < dist[e.to]) {
          dist[e.to] = dist[u] + e.cost;
          pred[e.to] = {u, &e};
          if (!active[e.to]) {
            q.push(e.to);
            active[e.to] = true;
          }
        }
      }
    }
    constexpr auto comp = [](const std::pair<int, Cost>& lhs,
                             const std::pair<int, Cost>& rhs) {
      return lhs.second > rhs.second;
    };
    std::priority_queue<std::pair<int, Cost>, std::vector<std::pair<int, Cost>>,
                        decltype(comp)>
        pq(comp);
    Flow total_flow = 0;
    Cost total_cost = 0, curr_cost = 0;
    while (dist[sink] != INF_COST) {
      Flow delta = max_flow - total_flow;
      for (int v = sink; v != source;) {
        const auto& [u, e] = pred[v];
        delta = std::min(delta, e->cap - e->flow);
        v = u;
      }
      for (int v = sink; v != source;) {
        const auto& [u, e] = pred[v];
        e->flow += delta;
        graph_[v][e->rev].flow -= delta;
        v = u;
      }
      total_cost += delta * (curr_cost += dist[sink]);
      if ((total_flow += delta) == max_flow) {
        break;
      }
      for (int u = 0; u < n; ++u) {
        for (edge& e : graph_[u]) {
          e.cost += dist[u] - dist[e.to];
        }
      }
      std::fill(dist.begin(), dist.end(), INF_COST);
      dist[source] = 0;
      pq.emplace(source, 0);
      while (!pq.empty()) {  // Dijkstra's shortest paths
        auto [u, d_u] = pq.top();
        pq.pop();
        if (d_u > dist[u]) {
          continue;
        }
        for (edge& e : graph_[u]) {
          if (e.flow < e.cap && dist[u] + e.cost < dist[e.to]) {
            pq.emplace(e.to, dist[e.to] = dist[u] + e.cost);
            pred[e.to] = {u, &e};
          }
        }
      }
    }
    int k = 0;
    for (std::vector<edge>& edges : graph_) {
      for (edge& e : edges) {
        e.cost = costs[k++];
      }
    }
    return std::pair(total_flow, total_cost);
  }

 private:
  struct edge {
    int to, rev;
    Flow cap, flow;
    Cost cost;

    constexpr edge(int _to, int _rev, Flow _cap, Cost _cost)
        : to(_to), rev(_rev), cap(_cap), cost(_cost) {}
  };

  static constexpr Cost INF_COST = std::numeric_limits<Cost>::max();
  int m_;
  std::vector<std::vector<edge>> graph_;
};

int main() {
  auto start_time = std::chrono::steady_clock::now();
  std::mt19937 thanos(
      (std::uint_fast32_t)start_time.time_since_epoch().count());
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  std::cout.precision(24);
  int n, m;
  cin >> n >> m;
  vector<string> board(n);
  for (int i = 0; i < n; ++i) {
    cin >> board[i];
  }
  min_cost_flow<int, int> flow(n * m + 2);
  int s = n * m, t = n * m + 1;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      if (board[i][j] == '#') {
        continue;
      }
      if (board[i][j] == 'o') {
        flow.add_edge(s, i * m + j, 1, 0);
      }
      flow.add_edge(i * m + j, t, 1, 0);
      if (i + 1 < n && board[i + 1][j] != '#') {
        flow.add_edge(i * m + j, (i + 1) * m + j, n * m, -1);
      }
      if (j + 1 < m && board[i][j + 1] != '#') {
        flow.add_edge(i * m + j, i * m + (j + 1), n * m, -1);
      }
    }
  }
  cout << -flow.solve(s, t).second << '\n';
  return 0;
}

Measured memory_bytes: 4264