#include<bits/stdc++.h>
#include<atcoder/all>
#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) \
  for (ll i = static_cast<int>(a); i < static_cast<int>(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, ) (__VA_ARGS__)  // NOLINT
#define chmax(x, a)  do { x = max(x, a); } while(0)
#define chmin(x, a)  do { x = min(x, a); } while(0)

using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef unsigned long long int ull;
typedef pair<ll,ll> PLL;

const ll dy[] = {1,0};
const ll dx[] = {0,1};
const ll INF = 101;

// {{{ min cost max flow
template< typename flow_t, typename cost_t >
struct PrimalDual {
  const cost_t INF;

  struct edge {
    int to;
    flow_t cap;
    cost_t cost;
    int rev;
    bool isrev;
  };
  vector< vector< edge > > graph;
  vector< cost_t > potential, min_cost;
  vector< int > prevv, preve;

  PrimalDual(int V) : graph(V), INF(numeric_limits< cost_t >::max()) {}

  void add_edge(int from, int to, flow_t cap, cost_t cost) {
    graph[from].emplace_back((edge) {to, cap, cost, (int) graph[to].size(), false});
    graph[to].emplace_back((edge) {from, 0, -cost, (int) graph[from].size() - 1, true});
  }

  cost_t min_cost_flow(int s, int t, flow_t f) {
    int V = (int) graph.size();
    cost_t ret = 0;
    using Pi = pair< cost_t, int >;
    priority_queue< Pi, vector< Pi >, greater< Pi > > que;
    potential.assign(V, 0);
    preve.assign(V, -1);
    prevv.assign(V, -1);

    while(f > 0) {
      min_cost.assign(V, INF);
      que.emplace(0, s);
      min_cost[s] = 0;
      while(!que.empty()) {
        Pi p = que.top();
        que.pop();
        if(min_cost[p.second] < p.first) continue;
        for(int i = 0; i < graph[p.second].size(); i++) {
          edge &e = graph[p.second][i];
          cost_t nextCost = min_cost[p.second] + e.cost + potential[p.second] - potential[e.to];
          if(e.cap > 0 && min_cost[e.to] > nextCost) {
            min_cost[e.to] = nextCost;
            prevv[e.to] = p.second, preve[e.to] = i;
            que.emplace(min_cost[e.to], e.to);
          }
        }
      }
      if(min_cost[t] == INF) return -1;
      for(int v = 0; v < V; v++) potential[v] += min_cost[v];
      flow_t addflow = f;
      for(int v = t; v != s; v = prevv[v]) {
        addflow = min(addflow, graph[prevv[v]][preve[v]].cap);
      }
      f -= addflow;
      ret += addflow * potential[t];
      for(int v = t; v != s; v = prevv[v]) {
        edge &e = graph[prevv[v]][preve[v]];
        e.cap -= addflow;
        graph[v][e.rev].cap += addflow;
      }
    }
    return ret;
  }

  void output() {
    for(int i = 0; i < graph.size(); i++) {
      for(auto &e : graph[i]) {
        if(e.isrev) continue;
        auto &rev_e = graph[e.to][e.rev];
        cout << i << "->" << e.to << " (flow: " << rev_e.cap << "/" << rev_e.cap + e.cap << ")" << endl;
      }
    }
  }
};
// }}}

ll N, M, K;

ll vid(ll y, ll x) {
  return y * M + x;
}

void solve() {
  cin >> N >> M;
  vector<string> a(N);
  rep(i, N)
    cin >> a[i];

  ll s = N * M + 1, e = N * M + 2;
  PrimalDual<ll, ll> g(N*M+1000);
  rep(y, N) rep(x, M) {
    ll i = vid(y, x);
    if (a[y][x] == 'o') {
      g.add_edge(s, i, 1, 0);
      K++;
    }
    if (a[y][x] == 'o' || a[y][x] == '.') {
      g.add_edge(i, e, 1, 0);
      rep(k, 2) {
        ll ny = y + dy[k], nx = x + dx[k];
        if (ny < 0 || ny >= N || nx < 0 || nx >= M || a[ny][nx] == '#') continue;
        g.add_edge(i, vid(ny,nx), INF, -1);
      }
    }
  }
  //auto t = g.flow(s,e);
  //for(auto e: g.edges()) {
  //  cout << e.from << " " << e.to << " " << e.flow << "/" << e.cap << endl;
  //}
  //cout << "flow: " << t.first << endl;
  //cout << "cost: " << t.second << endl;
  //cout << -t.second << endl;
	cout << - g.min_cost_flow(s,e,K) << endl;
}

int main() {
  //ll T;
  //cin >> T;
  //rep(_,T)
    solve();
  return 0;
}


Measured memory_bytes: 4468