#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

#define REP(i,n) for(ll i=0;i<(ll)n;i++)
#define dump(x)  cerr << "Line " << __LINE__ << ": " <<  #x << " = " << (x) << "\n";
#define spa << " " <<
#define fi first
#define se second
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()

using ld = long double;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;

template<typename T> using V = vector<T>;
template<typename T> using P = pair<T, T>;
template<typename T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<typename... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){os << "(" << v.first << ", " << v.second << ")"; return os;}
template<typename T> ostream& operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> ostream& operator<<(ostream& os, const vector<vector<T>> &v){ for(auto &e : v){os << e << "\n";} return os;}
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;

template <class T> void UNIQUE(vector<T> &x) {sort(ALL(x));x.erase(unique(ALL(x)), x.end());}
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
void fail() { cout << -1 << '\n'; exit(0); }
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
template<typename T> void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cerr<<v[i][0];for(ll j=1;j<w;j++)cerr spa v[i][j];cerr<<"\n";}};
template<typename T> void debug(vector<T>&v,ll n){if(n!=0)cerr<<v[0];
for(ll i=1;i<n;i++)cerr spa v[i];
cerr<<"\n";};

const ll INF = (1ll<<62);
// const ld EPS   = 1e-10;
// const ld PI    = acos(-1.0);
const ll mod = (int)1e9 + 7;
//const ll mod = 998244353;

int main(){

    ll N, M;
    cin >> N >> M;

    V<string> S(N);
    REP(i, N){
        cin >> S[i];
    }

    ll cnt = 0;
    V<ll> xx, yy;
    REP(i, N){
        REP(j, M){
            if(S[i][j] == 'o'){
                cnt++;
                xx.push_back(i);
                yy.push_back(j);
            }
        }
    }

    mcf_graph<ll, ll> G(cnt+N*M+2);
    const ll B = 5000;

    ll s = cnt+N*M;
    ll t = cnt+N*M+1;
    REP(i, cnt){
        //dump(i)
        G.add_edge(s, i, 1, 0);
    }
    REP(i, N*M){
        //dump(t)
        G.add_edge(cnt+i, t, 1, 0);
    }

    auto bfs = [&](ll x, ll y, ll idx){
        const int num_dir = 2;
        const int dx[] = {0, 1};
        const int dy[] = {1, 0}; 
        vector<vector<int>> dist(N, vector<int>(M, -1));
        queue<pair<int, int>> qu;
        qu.emplace(x, y);
        dist[x][y] = 0;

        while(!qu.empty()){
            auto p = qu.front();qu.pop();
            ll ci = p.first;
            ll cj = p.second;
            G.add_edge(idx, cnt+ci*M+cj, 1, B - dist[ci][cj]);
            // dump(idx)
            // dump(cnt+ci*M+cj)
            // dump(B - dist[ci][cj])
            for(int idx=0;idx<num_dir;idx++){
                int ni = p.first + dx[idx];
                int nj = p.second + dy[idx];

                if(ni<0 or nj<0 or ni>N-1 or nj>M-1) continue;
                if(dist[ni][nj] != -1) continue;
                if(S[ni][nj] == '#') continue;
                
                dist[ni][nj] = dist[p.first][p.second] + 1;
                qu.emplace(ni, nj);
            }
        }
    };

    REP(i, cnt) bfs(xx[i], yy[i], i);

    auto res = G.flow(s, t, cnt).second;
    // dump(res)

    res -= cnt*B;
    res *= -1;

    cout << res << endl;

    return 0;
}

Measured memory_bytes: 8776