#include<bits/stdc++.h>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

#define ll long long
#define ull unsigned ll

void reader(int *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(ll *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(double *x){scanf("%lf",x);}
int reader(char c[]){int i,s=0;for(;;){mygc(i);if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF) break;}c[s++]=i;for(;;){mygc(i);if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF) break;c[s++]=i;}c[s]='\0';return s;}
template <class T, class S> void reader(T *x, S *y){reader(x);reader(y);}
template <class T, class S, class U> void reader(T *x, S *y, U *z){reader(x);reader(y);reader(z);}
template <class T, class S, class U, class V> void reader(T *x, S *y, U *z, V *w){reader(x);reader(y);reader(z);reader(w);}

void writer(int x, char c){int s=0,m=0;char f[10];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(ll x, char c){int s=0,m=0;char f[20];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
void writer(double x, char c){printf("%.15f",x);mypc(c);}
void writer(const char c[]){int i;for(i=0;c[i]!='\0';i++)mypc(c[i]);}
void writer(const char x[], char c){int i;for(i=0;x[i]!='\0';i++)mypc(x[i]);mypc(c);}
template<class T> void writerLn(T x){writer(x,'\n');}
template<class T, class S> void writerLn(T x, S y){writer(x,' ');writer(y,'\n');}
template<class T, class S, class U> void writerLn(T x, S y, U z){writer(x,' ');writer(y,' ');writer(z,'\n');}
template<class T> void writerArr(T x[], int n){int i;if(!n){mypc('\n');return;}rep(i,n-1)writer(x[i],' ');writer(x[n-1],'\n');}

char memarr[17000000]; void *mem = memarr;
#define MD 1000000007

int X, Y;
char mp[1111][1111];

int dx[8] = {0,0,1,-1,1,1,-1,-1};
int dy[8] = {1,-1,0,0,1,-1,1,-1};


int nul(int a, int b, char f, char t, int d, int st[], int &sts){
  int i,res = 0;

  if(a < 0 || b < 0 || a >= X || b >= Y) return res;
  if(mp[a][b] != f){
    if(mp[a][b]=='x'){
      st[sts++] = a*1111+b;
      mp[a][b] = 'y';
    }
    return res;
  }

  mp[a][b] = t;
  res++;

  rep(i,d) res += nul(a+dx[i],b+dy[i],f,t,d,st,sts);
  return res;
}

int node;
vector<int> edge[1111111];
int es[1111111], gain[1111111];

void gen_graph(int st[], int sts, int bef){
  int i, j, k, g;
  int *sss = st + sts;
  int ssz;
  
  rep(k,sts){
    i = st[k] / 1111;
    j = st[k] % 1111;
    if(mp[i][j] != 'y') continue;

    ssz = 0;
    g = nul(i,j,'y','.',8,sss,ssz);
    es[node] = 0;
    gain[node] = g;
    if(bef!=-1) edge[bef].push_back(node);
    node++;

    ssz = 0;
    nul(i,j,'.','@',4,sss,ssz);
    gen_graph(sss,ssz,node-1);
  }
}

int st[1111111], sts;

int dp0[1111111], dp1[1111111];
int solve(int now, int bef){
  int i, j, k;

  dp0[now] = 0;
  dp1[now] = gain[now];
  rep(i,edge[now].size()){
    j = edge[now][i];
    if(j==bef) continue;
    solve(j, now);
    dp0[now] += dp1[j];
    dp1[now] += dp0[j];
  }

  dp1[now] = max(dp0[now], dp1[now]);
  return dp1[now];
}

int main(){
  int i, j, k;
  int res;

  reader(&X,&Y);
  X += 2;
  Y += 2;
  REP(i,1,X-1) reader(mp[i]+1);

  rep(i,Y) mp[0][i] = mp[X-1][i] = '.';
  rep(i,X) mp[i][0] = mp[i][Y-1] = '.';

  node = 1;
  sts = 0;
  nul(0,0,'.','@',4,st,sts);
  gen_graph(st, sts, 0);

  res = solve(0,-1);
  writerLn(res);

  return 0;
}