#include <bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
using namespace std;
typedef long long ll;
typedef pair<int,int>P;

const int MOD=1000000007;
const int INF=0x3f3f3f3f;
const ll INFL=0x3f3f3f3f3f3f3f3f;

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) : INF(numeric_limits< cost_t >::max()),graph(V) {}
 
  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 output() {
    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;
      }
    }
  }
};

string s[60];
bool used[60][60];

int dx[]{1,0},dy[]{0,1};
int main(){
	int n,m;cin>>n>>m;
	rep(i,n)cin>>s[i];
	PrimalDual<int,int>f(n*m+2);
	int S=n*m,T=n*m+1;
	int B=200;
	int cnt=0;
	int d=0;
	rep(i,n)rep(j,m){
		if(s[i][j]!='o')continue;
		d+=i+j;
		cnt++;
		f.add_edge(S,i*m+j,1,0);
		queue<P>que;
		memset(used,0,sizeof(used));
		used[i][j]=true;
		que.push(P(i,j));
		while(!que.empty()){
			P p=que.front();que.pop();
			rep(k,2){
				int nx=p.first+dx[k],ny=p.second+dy[k];
				if(0<=nx&&nx<n&&0<=ny&&ny<m&&s[nx][ny]!='#'&&!used[nx][ny]){
					used[nx][ny]=true;
					que.push(P(nx,ny));
				}
			}
		}
		rep(k,n)rep(t,m){
			if(used[k][t]){
				f.add_edge(i*m+j,k*m+t,1,0);
			}
		}
	}
	rep(i,n)rep(j,m){
		f.add_edge(i*m+j,T,1,B-i-j);
	}
	cout<<B*cnt-f.min_cost_flow(S,T,cnt)-d<<endl;
}

Measured memory_bytes: 7476