//@formatter:off
#include<bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < int(n); ++i)
#define rrep(i,n) for (int i = int(n)-1; i >= 0; i--)
#define rep2(i,s,n) for (int i = int(s); i < int(n); ++i)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define vvi vector<vector<int>>
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vd vector<double>
#define vvd vector<vector<double>>
#define vs vector<string>
#define vc vector<char>
#define vvc vector<vector<char>>
#define vb vector<bool>
#define vvb vector<vector<bool>>
#define vp vector<P>
#define vvp vector<vector<P>>
using namespace std;
using ll = long long;
using P = pair<int,int>;
using LP = pair<ll,ll>;
template<class S,class T> istream& operator>>(istream &is,pair<S,T> &p) { return is >> p.first >> p.second; }
template<class S,class T> ostream& operator<<(ostream &os,const pair<S,T> &p) { return os<<'{'<<p.first<<","<<p.second<<'}'; }
template<class T> istream& operator>>(istream &is,vector<T> &v) { for(T &t:v){is>>t;} return is; }
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) { os<<'[';rep(i,v.size())os<<v[i]<<(i==int(v.size()-1)?"":","); return os<<']'; }
void Yes(bool b) { cout << (b ? "Yes" : "No") << '\n'; }
void YES(bool b) { cout << (b ? "YES" : "NO") << '\n'; }
template<class T> bool chmin(T& a,T b) {if(a > b){a = b; return true;} return false;}
template<class T> bool chmax(T& a,T b) {if(a < b){a = b; return true;} return false;}
const int inf = 1001001001;
const ll linf = 1001001001001001001;
//@formatter:on

template<typename T>
class Mincostflow {
    using TP = pair<T, int>;
    
    struct edge {
        int to, cap, rev;
        T cost;
        
        edge(int to, int cap, T cost, int rev) : to(to), cap(cap), cost(cost), rev(rev) {}
    };
    
    T tinf;
    int n;
    vector<vector<edge>> G;
    vector<T> pot, dist;
    vi prevv, preve;
    
    // potential
    void tinf_init(int x) { tinf = inf; }
    
    void tinf_init(ll x) { tinf = linf; }

public:
    explicit Mincostflow(int n) : n(n), G(n), pot(n), dist(n), prevv(n), preve(n) {
        T x = 0;
        tinf_init(x);
    }
    
    void add_edge(int from, int to, T cap, int cost) {
        G[from].eb(to, cap, cost, G[to].size());
        G[to].eb(from, 0, -cost, G[from].size() - 1);
    }
    
    // return -1 if impossible
    // this must not be called more than once
    T min_cost_flow(int s, int t, int f) {
        T res = 0;
        pot.assign(n, 0);
        while (f > 0) {
            // use dijkstra to update pot
            priority_queue<TP, vector<TP>, greater<TP>> q;
            dist.assign(n, tinf);
            dist[s] = 0;
            q.emplace(0, s);
            while (!q.empty()) {
                T np = q.top().first;
                int v = q.top().second;
                q.pop();
                if (dist[v] < np) continue;
                rep(i, G[v].size()) {
                    edge &e = G[v][i];
                    if (e.cap > 0 && dist[e.to] > dist[v] + e.cost + pot[v] - pot[e.to]) {
                        dist[e.to] = dist[v] + e.cost + pot[v] - pot[e.to];
                        prevv[e.to] = v;
                        preve[e.to] = i;
                        q.emplace(dist[e.to], e.to);
                    }
                }
            }
            if (dist[t] == tinf) return -1;
            rep(i, n) pot[i] += dist[i];
            
            int d = f;
            for (int v = t; v != s; v = prevv[v]) {
                chmin(d, G[prevv[v]][preve[v]].cap);
            }
            f -= d;
            res += d * pot[t];
            for (int v = t; v != s; v = prevv[v]) {
                edge &e = G[prevv[v]][preve[v]];
                e.cap -= d;
                G[v][e.rev].cap += d;
            }
        }
        return res;
    };
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, m;
    cin >> n >> m;
    int sz = n * m;
    vs v(n);
    cin >> v;
    Mincostflow<int> fl(2 * sz + 2);
    int s = 2 * sz;
    int t = s + 1;
    rep(i, sz) fl.add_edge(sz + i, t, 1, 0);
    int ans = 0, cnt = 0;
    rep(i, n) rep(j, m) {
            char c = v[i][j];
            if (c == 'o') {
                cnt++;
                vvb d(n, vb(m));
                d[i][j] = true;
                queue<P> q;
                q.emplace(i, j);
                while (q.size()) {
                    auto[i, j] = q.front();
                    q.pop();
                    if (i + 1 < n) {
                        if (!d[i + 1][j] and v[i + 1][j] != '#') {
                            d[i + 1][j] = true;
                            q.emplace(i + 1, j);
                        }
                    }
                    if (j + 1 < m) {
                        if (!d[i][j + 1] and v[i][j + 1] != '#') {
                            d[i][j + 1] = true;
                            q.emplace(i, j + 1);
                        }
                    }
                }
                int mx = 0;
                rep(ni, n) rep(nj, m) {
                        if (d[ni][nj]) chmax(mx, ni - i + nj - j);
                    }
                ans += mx;
                fl.add_edge(s, i * m + j, 1, 0);
                rep(ni, n) rep(nj, m) {
                        if (d[ni][nj]) {
                            fl.add_edge(i * m + j, ni * m + nj + sz, 1, mx - (ni - i + nj - j));
                        }
                    }
            }
        }
    cout << ans - fl.min_cost_flow(s, t, cnt) << endl;
}

Measured memory_bytes: 6572