#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


struct UnionFind{
  Int n;
  vector<Int> r,p;
  UnionFind(){}
  UnionFind(Int sz):n(sz),r(sz,1),p(sz,0){iota(p.begin(),p.end(),0);}
  Int find(Int x){
    return (x==p[x]?x:p[x]=find(p[x]));
  }
  bool same(Int x,Int y){
    return find(x)==find(y);
  }
  void unite(Int x,Int y){
    x=find(x);y=find(y);
    if(x==y) return;
    if(r[x]<r[y]) swap(x,y);
    r[x]+=r[y];
    p[y]=x;
  }
};

//INSERT ABOVE HERE
signed main(){
  Int h,w;
  cin>>h>>w;
  h++;
  vector<string> s(h);
  s[0]=string(w,'.');
  for(Int i=1;i<h;i++) cin>>s[i];

  Int n=h*w+1;
  UnionFind uf(n);
  auto idx=[&](Int i,Int j){return i*w+j;};
  for(Int i=0;i<h;i++){
    for(Int j=0;j<w;j++){
      if(s[i][j]!='x') continue;
      if(i+1<h&&s[i+1][j]=='x')
        uf.unite(idx(i,j),idx(i+1,j));
      if(j+1<w&&s[i][j+1]=='x')
        uf.unite(idx(i,j),idx(i,j+1));
      if(i+1<h&&j+1<w&&s[i+1][j+1]=='x')
        uf.unite(idx(i,j),idx(i+1,j+1));      
      if(i-1>=0&&j+1<w&&s[i-1][j+1]=='x')
        uf.unite(idx(i,j),idx(i-1,j+1));
    }
  }
  vector<set<Int> > G(n);  
  vector<Int> sz(n);  
  Int dy[]={0,0,1,-1};
  Int dx[]={1,-1,0,0};
  
  vector<Int> used(n,0);
  auto in=[&](Int y,Int x){return 0<=y&&y<h&&0<=x&&x<w;};
  using T = tuple<Int, Int, Int>;
  queue<T> qt;
  qt.emplace(0,0,h*w);
  while(!qt.empty()){
    Int sy,sx,c;
    tie(sy,sx,c)=qt.front();qt.pop();
    using P = pair<Int, Int>;
    queue<P> q;
      
    used[idx(sy,sx)]=1;
    q.emplace(sy,sx);
    while(!q.empty()){
      Int y,x;
      tie(y,x)=q.front();q.pop();
      for(Int k=0;k<4;k++){
        Int ny=y+dy[k],nx=x+dx[k];
        Int nz=idx(ny,nx);
        if(!in(ny,nx)||used[nz]) continue;
        if(s[ny][nx]=='x'){
          if(!uf.same(c,nz)){
            G[c].emplace(uf.find(nz));
            qt.emplace(ny,nx,uf.find(nz));
          }else{            
            used[nz]=1;
            q.emplace(ny,nx);
          }
        }else{
          used[nz]=1;
          q.emplace(ny,nx);
        }
      }        
    }      
  }
  
  vector<Int> dp1(n),dp2(n);
  function<void(Int)> dfs=
    [&](Int v)->void{     
      if(uf.r[v]>1) dp1[v]=uf.r[v];
      for(Int u:G[v]){
        //cout<<v<<"->"<<u<<endl;
        dfs(u);
        dp1[v]+=dp2[u];
        dp2[v]+=dp1[u];
      }      
      chmax(dp1[v],dp2[v]);
    };
  
  dfs(h*w);
  cout<<dp1[h*w]<<endl;
  return 0;
}