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

#define ALL(obj) (obj).begin(),(obj).end()
template<class T> using priority_queue_reverse = priority_queue<T,vector<T>,greater<T>>;

constexpr long long MOD = 1'000'000'000LL + 7;
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433L;

template <class T> vector<T> multivector(size_t N,T init){return vector<T>(N,init);}
template <class... T> auto multivector(size_t N,T... t){return vector<decltype(multivector(t...))>(N,multivector(t...));}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template <class T, class U>ostream &operator<<(ostream &o, const map<T, U>&obj) {o << "{"; for (auto &x : obj) o << " {" << x.first << " : " << x.second << "}" << ","; o << " }"; return o;}
template <class T>ostream &operator<<(ostream &o, const set<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const multiset<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const vector<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T, class U>ostream &operator<<(ostream &o, const pair<T, U>&obj) {o << "{" << obj.first << ", " << obj.second << "}"; return o;}
void print(void) {cout << endl;}
template <class Head> void print(Head&& head) {cout << head;print();}
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) {cout << head << " ";print(forward<Tail>(tail)...);}
template <class T> void chmax(T& a, const T b){a=max(a,b);}
template <class T> void chmin(T& a, const T b){a=min(a,b);}
vector<string> split(const string &str, const char delemiter) {vector<string> res;stringstream ss(str);string buffer; while( getline(ss, buffer, delemiter) ) res.push_back(buffer); return res;}
int msb(int x) {return x?31-__builtin_clz(x):-1;}
void YN(bool flg) {cout << (flg ? "YES" : "NO") << endl;}
void Yn(bool flg) {cout << (flg ? "Yes" : "No") << endl;}
void yn(bool flg) {cout << (flg ? "yes" : "no") << endl;}

int main() {
    cin.tie(0);ios::sync_with_stdio(false);
    int H,W; cin >> H >> W;
    vector<string> vs(H);
    vector<int> cy,cx;
    for(int i = 0; i < H; ++i) {
        cin >> vs[i];
        for(int j = 0; j < W; ++j) {
            if(vs[i][j]=='o') cy.push_back(i),cx.push_back(j);
        }
    }
    ll c = cy.size();
    ll inf = 123456789;
    atcoder::mcf_graph<int,ll> mcf(c+H*W+2);
    int s = c+H*W,g = c+H*W+1;
    for(int i = 0; i < c; ++i) {
        int ty = cy[i],tx = cx[i];
        auto dp = multivector(H,W,-1LL);
        queue<int> q;
        q.push(ty*W+tx);
        dp[ty][tx]=0;
        while(q.size()){
            auto p=q.front(); q.pop();
            int y = p/W, x = p%W;
            if(y+1<H && vs[y+1][x]!='#' && dp[y+1][x] == -1) {
                dp[y+1][x]=dp[y][x]+1;
                q.push((y+1)*W+x);
            }
            if(x+1<W && vs[y][x+1]!='#' && dp[y][x+1] == -1) {
                dp[y][x+1]=dp[y][x]+1;
                q.push(y*W+x+1);
            }
        }
        for(int y=0; y < H; ++y) {
            for(int x=0; x < W; ++x) {
                if(dp[y][x]!=-1) {
                    mcf.add_edge(i,c+y*W+x,1,inf-dp[y][x]);
                }
            }
        }
        mcf.add_edge(s,i,1,0);
    }
    {
        for(int y=0; y < H; ++y) {
            for(int x=0; x < W; ++x) {
                mcf.add_edge(c+y*W+x,g,1,0);
            }
        }
    }
    ll ans = inf*c;
    auto p = mcf.flow(s,g);
    ans -= p.second;
    cout << ans << endl;
    return 0;
}


Measured memory_bytes: 8872