#line 1 "main.cpp"

/**
 * @title Template
 */

#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>
#include <cassert>
#include <atcoder/mincostflow.hpp>

#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/other/chmin_chmax.cpp"

template <class T, class U>
constexpr bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) { lhs = rhs; return true; }
  return false;
}

template <class T, class U>
constexpr bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) { lhs = rhs; return true; }
  return false;
}

/**
 * @title Chmin/Chmax
 */
#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/other/range.cpp"

#line 4 "/Users/kodamankod/Desktop/cpp_programming/Library/other/range.cpp"

class range {
public:
  class iterator {
  private:
    int64_t M_position;

  public:
    constexpr iterator(int64_t position) noexcept: M_position(position) { }
    constexpr void operator ++ () noexcept { ++M_position; }
    constexpr bool operator != (iterator other) const noexcept { return M_position != other.M_position; }
    constexpr int64_t operator * () const noexcept { return M_position; }
  };

  class reverse_iterator {
  private:
    int64_t M_position;
  
  public:
    constexpr reverse_iterator(int64_t position) noexcept: M_position(position) { }
    constexpr void operator ++ () noexcept { --M_position; }
    constexpr bool operator != (reverse_iterator other) const noexcept { return M_position != other.M_position; }
    constexpr int64_t operator * () const noexcept { return M_position; }
  };
  
private:
  const iterator M_first, M_last;

public:
  constexpr range(int64_t first, int64_t last) noexcept: M_first(first), M_last(std::max(first, last)) { }
  constexpr iterator begin() const noexcept { return M_first; }
  constexpr iterator end() const noexcept { return M_last; }
  constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator(*M_last - 1); } 
  constexpr reverse_iterator rend() const noexcept { return reverse_iterator(*M_first - 1); } 
};

/**
 * @title Range
 */
#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/other/rev.cpp"

#include <type_traits>
#include <iterator>
#line 6 "/Users/kodamankod/Desktop/cpp_programming/Library/other/rev.cpp"

template <class T>
class rev_impl {
public:
  using iterator = decltype(std::rbegin(std::declval<T>()));

private:
  const iterator M_begin;
  const iterator M_end;

public:
  constexpr rev_impl(T &&cont) noexcept: M_begin(std::rbegin(cont)), M_end(std::rend(cont)) { }
  constexpr iterator begin() const noexcept { return M_begin; }
  constexpr iterator end() const noexcept { return M_end; }
};

template <class T>
constexpr decltype(auto) rev(T &&cont) {
  return rev_impl<T>(std::forward<T>(cont));
}

/**
 * @title Reverser
 */
#line 18 "main.cpp"

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;

constexpr i32 inf32 = (i32(1) << 30) - 1;
constexpr i64 inf64 = (i64(1) << 62) - 1;

int main() {
  i32 N, M;
  std::cin >> N >> M;
  std::vector<std::vector<bool>> cango(N, std::vector<bool>(M));
  std::vector<std::pair<i32, i32>> vec;
  for (auto i: range(0, N)) {
    for (auto j: range(0, M)) {
      char c;
      std::cin >> c;
      cango[i][j] = (c != '#');
      if (c == 'o') {
        vec.emplace_back(i, j);
      }
    }
  }
  const i32 size = vec.size();
  atcoder::mcf_graph<i64, i64> net(N * M + size + 2);
  const auto src = N * M + size;
  const auto sink = N * M + size + 1;
  for (auto i: range(0, N)) {
    for (auto j: range(0, M)) {
      if (cango[i][j]) {
        net.add_edge(i * M + j, sink, 1, 0);
      }
    }
  }
  for (auto i: range(0, size)) {
    const auto [sx, sy] = vec[i];
    std::vector<std::vector<i32>> reach(N, std::vector<i32>(M, -1));
    reach[sx][sy] = 0;
    for (auto x: range(0, N)) {
      for (auto y: range(0, M)) {
        if (cango[x][y]) {
          if (x > 0 && reach[x - 1][y] != -1) {
            reach[x][y] = reach[x - 1][y] + 1;
          }
          if (y > 0 && reach[x][y - 1] != -1) {
            reach[x][y] = reach[x][y - 1] + 1;
          }
          if (reach[x][y] != -1) {
            net.add_edge(N * M + i, x * M + y, 1, inf32 - reach[x][y]);   
          }
        }
      }
    }
    net.add_edge(src, N * M + i, 1, 0);
  }
  std::cout << (i64) inf32 * size - net.flow(src, sink).second << '\n';
  return 0;
}


Measured memory_bytes: 8744