#include <atcoder/all>
#include <bits/stdc++.h>
#define int long long
#define sint signed
#define endl "\n" // fflush(stdout);
#define ALL(v) (v).begin(),(v).end()
#define Vi vector<int>
#define VVi vector<Vi>
#define VVVi vector<VVi>
#define Vm vector<mint>
#define Vs vector<string>
#define Vd vector<double>
#define Vc vector<char>
#define Pii pair<int,int>
#define Pdd pair<double,double>
#define VPii vector<Pii>
#define Tiii tuple<int,int,int>
#define VTiii vector<Tiii>
#define PQi priority_queue<int>
#define PQir priority_queue<int,vector<int>,greater<int>>
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define itos to_string
#define stoi stoll
#define FI first
#define SE second
#define cYES cout<<"YES"<<endl
#define cNO cout<<"NO"<<endl
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define cyes cout<<"yes"<<endl
#define cno cout<<"no"<<endl
#define sortr(v) sort(v,greater<>())
#define rep(i,a,b) for(int i=a;i<b;i++)
#define repeq(i,a,b) for(int i=a;i<=b;i++)
#define repreq(i,a,b) for(int i=a;i>=b;i--)
#define dem(a,b) ((a+b-1)/(b))
#define INF 3000000000000000000 // 3.0*10^18
#define MAX LLONG_MAX
#define PI acos(-1.0L)

using namespace std;
using namespace atcoder;

/* debug */
template <typename T>
ostream& operator<<(ostream& os,const vector<T> &V){int N=V.size();
if(N==0){os<<'.';return os;}rep(i,0,N-1){os<<V[i]<<' ';}os<<V[N-1];return os;}
template <typename T>
ostream& operator<<(ostream& os,const vector<vector<T>> &V){
int N=V.size();rep(i,0,N-1)os<<V[i]<<endl;os<<V[N-1];return os;}
template <typename T,typename S>
ostream& operator<<(ostream& os, pair<T,S> const&P){os<<P.FI<<' '<<P.SE;return os;}

/* useful */
template<typename T>void Vin(vector<T> &v){int n=v.size();rep(i,0,n)cin>>v[i];}
int scomb(int n, int r){if(r<0||r>n)return 0;if((n-r)<r)r=n-r; // nCr
int a=1;for(int i=n;i>n-r;--i){a=a*i;}for(int i=1;i<r+1;++i){a=a/i;}return a;}
Vi vis(Vi &v){Vi S(v.size()+1);rep(i,1,S.size())S[i]+=v[i-1]+S[i-1];return S;}
int digit_sum(int n){int ret=0; while(n>0){ret+=n%10;n/=10;}return ret;}
int digit(int k,int i){string s = itos(k);return s[s.size()-i]-'0';} // i桁目の数字
template<typename T>void press(T &v){v.erase(unique(ALL(v)),v.end());} // 圧縮
Vi zip(Vi b){int Z=b.size(); // 座標圧縮
Pii p[Z+10];int a=b.size();Vi l(a);for(int i=0;i<a;i++)
p[i]=mp(b[i],i);sort(p,p+a);int w=0;for(int i=0;i<a;i++)
{if(i&&p[i].first!=p[i-1].first)w++;l[p[i].second]=w;}return l;}
int SMALLER(Vi &a,int x){return lower_bound(a.begin(),a.end(),x)-a.begin();}
int orSMALLER(Vi &a,int x){return upper_bound(a.begin(),a.end(),x)-a.begin();}
int BIGGER(Vi &a,int x){return a.size()-orSMALLER(a,x);}
int orBIGGER(Vi &a,int x){return a.size()-SMALLER(a,x);}
int COUNT(Vi &a,int x) {return upper_bound(ALL(a),x)-lower_bound(ALL(a),x);}
int maxind(Vi &a){return max_element(ALL(a))-a.begin();}
int minind(Vi &a){return min_element(ALL(a))-a.begin();}

//const int MOD = 998244353;
const int MOD = 1000000007;
const double EPS = 1e-10;
using mint = modint;

void init(){cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);
cout<<fixed<<setprecision(12);mint::set_mod(MOD);}

/************************************ START ************************************/

const long long BIG = 100000;



signed main() {
  init();
  int h,w;cin >> h >> w;
  auto in = [&] (int i,int j) {
    if(i < 0 || j < 0 || i >= h || j >= w) return 0;
    else return 1;
  };
  int ct = 0;
  Vs mapp(h);Vin(mapp);
  VVi co(h,Vi(w));
  rep(i,0,h)rep(j,0,w) co[i][j] = i+j;
  rep(i,0,h)rep(j,0,w) if(mapp[i][j]=='o') ct++;
  //cout << co << endl;
  mcf_graph<int, long long> g(h*w + 2);
  int s = h*w, t = h*w + 1;
  int M = 10000;
  //g.add_edge(s, t, M, BIG);
  rep(i,0,h)rep(j,0,w){
    if(mapp[i][j]=='o') g.add_edge(s, i*w+j, 1, co[i][j]);
    if(in(i+1,j) && mapp[i][j] != '#' && mapp[i+1][j] != '#'){
      g.add_edge(i*w+j, (i+1)*w+j, M, 0);
    }
    if(in(i,j+1) && mapp[i][j] != '#' && mapp[i][j+1] != '#'){
      g.add_edge(i*w+j, i*w+j+1, M, 0);
    }
    if(mapp[i][j] != '#'){
      g.add_edge(i*w+j,t, 1, BIG-co[i][j]);
    }
  }
  auto result = g.flow(s, t, ct);
  cout << BIG*ct-result.SE << endl;
  return 0;
}

Measured memory_bytes: 4340