#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// #include<ext/pb_ds/tag_and_trait.hpp>
// using namespace __gnu_pbds;
// #include<boost/multiprecision/cpp_int.hpp>
// namespace multiprecisioninteger = boost::multiprecision;
// using cint=multiprecisioninteger::cpp_int;
using namespace std;
using ll=long long;
#define double long double
using datas=pair<ll,ll>;
using ddatas=pair<double,double>;
using tdata=pair<ll,datas>;
using vec=vector<ll>;
using mat=vector<vec>;
using pvec=vector<datas>;
using pmat=vector<pvec>;
// using llset=tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>;
#define For(i,a,b) for(i=a;i<(ll)b;++i)
#define bFor(i,b,a) for(i=b,--i;i>=(ll)a;--i)
#define rep(i,N) For(i,0,N)
#define rep1(i,N) For(i,1,N)
#define brep(i,N) bFor(i,N,0)
#define brep1(i,N) bFor(i,N,1)
#define all(v) (v).begin(),(v).end()
#define allr(v) (v).rbegin(),(v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define endl "\n"
#define eb emplace_back
#define print(v) cout<<v<<endl
#define printyes cout<<"Yes"<<endl
#define printno cout<<"No"<<endl
#define printYES cout<<"YES"<<endl
#define printNO cout<<"NO"<<endl
#define output(v) do{bool f=0;for(auto outi:v){cout<<(f?" ":"")<<outi;f=1;}cout<<endl;}while(0)
#define matoutput(v) do{for(auto outimat:v)output(outimat);}while(0)
const ll mod=1000000007;
// const ll mod=998244353;
const ll inf=1LL<<60;
const double PI = acos(-1);
const double eps = 1e-9;
template<class T> inline bool chmax(T& a,T b){bool x=a<b;if(x)a=b;return x;} 
template<class T> inline bool chmin(T& a,T b){bool x=a>b;if(x)a=b;return x;} 

void startupcpp(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout<<fixed<<setprecision(15);
}

double distance(ddatas x,ddatas y){
  double a=x.first-y.first,b=x.second-y.second;
  return sqrt(a*a+b*b);
}

ll modinv(ll a,ll m=mod) {
  ll b=m,u=1,v=0,t;
  while(b){
    t=a/b;
    a-=t*b; swap(a,b);
    u-=t*v; swap(u,v);
  }
  return (u+m)%m;
}

ll moddevide(ll a,ll b){return (a*modinv(b))%mod;}

vec modncrlistp,modncrlistm;

ll modncr(ll n,ll r){
  if(n<r)return 0;
  ll i,size=modncrlistp.size();
  if(size<=n){
    modncrlistp.resize(n+1);
    modncrlistm.resize(n+1);
    if(!size){
      modncrlistp[0]=modncrlistm[0]=1;
      size++;
    }
    For(i,size,n+1){
      modncrlistp[i]=modncrlistp[i-1]*i%mod;
      modncrlistm[i]=modinv(modncrlistp[i]);
    }
  }
  return modncrlistp[n]*modncrlistm[r]%mod*modncrlistm[n-r]%mod;
}

ll modpow(ll a,ll n,ll m=mod){
  ll res=1;
  while(n>0){
    if(n&1)res=res*a%m;
    a=a*a%m;
    n>>=1;
  }
  return res;
}

ll gcd(ll a,ll b){if(!b)return abs(a);return (a%b==0)?abs(b):gcd(b,a%b);}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

ll countdigits(ll n){
  ll ans=0;
  while(n){n/=10;ans++;}
  return ans;
}

ll sumdigits(ll n){
  ll ans=0;
  while(n){ans+=n%10;n/=10;}
  return ans;
}
template <typename T>
struct BinaryIndexedTree{
  int size,bitn=0;
  T I;
  using func=function<T(T,T)>;
  func F;
  vector<T> tree;
  BinaryIndexedTree(int N,T e,func f):size(N+1),I(e),F(f),tree(size,e){}
  BinaryIndexedTree(int N):size(N+1),I(0),F([](T a,T b){return a+b;}),tree(size,0){}
  void act(int i,T x){
    for(++i;i<size;i+=-i&i){
      tree[i]=F(tree[i],x);
    }
  }
  //return F([0,i]);
  T queli(int i){
    T res=I;
    for(++i;i>0;i-=-i&i){
      res=F(tree[i],res);
    }
    return res;
  }
  //sum([l,r));
  T sum(int l,int r){
    // if(--l>--r)return 0;
    assert(--l<=--r);
    if(l<0)return queli(r);
    else return queli(r)-queli(l);
  }
  //only(N,+)
  int lower_bound(int x){
    int i=0;
    if(!bitn){
      i=size;bitn=1;
      while(i){
        i>>=1;bitn<<=1;
      }
      i=0;
    }
    for(int k=bitn;k;k>>=1){
      if(i+k<size&&tree[i+k]<x){
        i+=k;
        x-=tree[i];
      }
    }
    return i;
  }
};
struct unionfind{
  private:
  int maxN;
  vector<int> par,treesize;
  public:unionfind(int N) :maxN(N),par(N),treesize(N,1){
    for(int i=0;i<maxN;++i)par[i]=i;
  }
  int root(int x){
    while(par[x]!=x){
      x=par[x]=par[par[x]];
    }
    return x;
  }
  bool unite(int x,int y){
    x=root(x);
    y=root(y);
    if(x==y)return false;
    if(treesize[x]>treesize[y])swap(x,y);
    par[x]=y;
    treesize[y]+=treesize[x];
    return true;
  }
  bool parcheck(int x,int y){
    return root(x)==root(y);
  }
  int size(int x){
    return treesize[root(x)];
  }
  void clear(){
    treesize.assign(maxN,1);
    for(int i=0;i<maxN;++i)par[i]=i;
  }
  vector<vector<int>> groups(){
    vector<vector<int>> res(maxN);
    for(int i=0;i<maxN;++i)res[root(i)].eb(i);
    return res;
    vector<vector<int>> res2;
    for(vector<int> x:res){
      if(x.size())res2.eb(x);
    }
    return res2;
  }
};
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 printout() {
    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,H,W,A,B,C,D;
string s,t;
ll ans;
int main(){
  startupcpp();
  // int codeforces;cin>>codeforces;while(codeforces--){
  ll i,j,cnt=0;
  cin>>H>>W;
  vector<string> s(H);
  PrimalDual<ll,ll> flow(H*W*2+2);
  rep(i,H){
    cin>>s[i];
    rep(j,W){
      flow.add_edge((i+H)*W+j,H*W*2+1,1,0);
      if(s[i][j]=='o'){
        cnt++;flow.add_edge(H*W*2,i*W+j,1,0);
      }
      if(s[i][j]!='#'){
        flow.add_edge((i+H)*W+j,i*W+j,cnt,0);
        flow.add_edge(i*W+j,(i+H)*W+j,cnt,0);
        if(i&&s[i-1][j]!='#'){
          flow.add_edge((i-1)*W+j,(i+H)*W+j,cnt,-1);
        }
        if(j&&s[i][j-1]!='#'){
          flow.add_edge(i*W+j-1,(i+H)*W+j,cnt,-1);
        }
      }
    }
  }
  print(-flow.min_cost_flow(H*W*2,H*W*2+1,cnt));
}

Measured memory_bytes: 4808