/* -*- coding: utf-8 -*-
 *
 * 348.cc: No.348 カゴメカゴメ - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 1000;
const int MAX_M = 1000;
const int MAX_T = MAX_N * MAX_M / 3 + 1;

const int dxs[] = {1, 1, 0, -1, -1, -1, 0, 1};
const int dys[] = {0, -1, -1, -1, 0, 1, 1, 1};

const int INF = 1 << 30;

/* typedef */

typedef vector<int> vi;
typedef queue<int> qi;
typedef pair<int,int> pii;

/* global variables */

int n, m, nm;
string lines[MAX_N];
int used[MAX_N][MAX_M];
int prts[MAX_T], wis[MAX_T];
vi chlds[MAX_T];
int dp[MAX_T][2];

/* subroutines */

void print_flds() {
  for (int y = 0; y < n; y++) {
    for (int x = 0; x < m; x++) printf("%2d ", used[y][x]);
    putchar('\n');
  }
}

int adj_ids(int x, int y, int ddi = 1) {
  int maxid = -1;
  for (int di = 0; di < 8; di += ddi) {
    int vx = x + dxs[di], vy = y + dys[di];
    int id = (vx >= 0 && vx < m && vy >= 0 && vy < n) ? used[vy][vx] : 0;
    if (maxid < id) maxid = id;
  }
  return maxid;
}

inline int adj4_ids(int x, int y) { return adj_ids(x, y, 2); }

int paint(int x0, int y0, int id, char ch, int ddi = 1) {
  if (lines[y0][x0] != ch || used[y0][x0] >= 0) return 0;

  int pn = 1;
  used[y0][x0] = id;
  queue<pii> q;
  q.push(pii(x0, y0));

  while (! q.empty()) {
    pii u = q.front(); q.pop();
    int &ux = u.first, &uy = u.second;

    for (int di = 0; di < 8; di += ddi) {
      int vx = ux + dxs[di], vy = uy + dys[di];
      if (vx >= 0 && vx < m && vy >= 0 && vy < n &&
	  lines[vy][vx] == ch && used[vy][vx] < 0) {
	pn++;
	used[vy][vx] = id;
	q.push(pii(vx, vy));
      }
    }
  }

  return pn;
}

inline int paint4(int x0, int y0, int id, char ch) {
  return paint(x0, y0, id, ch, 2);
}

void rec(int u) {
  dp[u][0] = 0;
  dp[u][1] = wis[u];
  
  vi &chldu = chlds[u];
  for (vi::iterator vit = chldu.begin(); vit != chldu.end(); vit++) {
    int &v = *vit;
    rec(v);
    dp[u][0] += max(dp[v][0], dp[v][1]);
    dp[u][1] += dp[v][0];
  }
}

/* main */

int main() {
  cin >> n >> m;
  for (int y = 0; y < n; y++) cin >> lines[y];
  nm = n * m;

  memset(used, -1, sizeof(used));
  prts[0] = -1;

  int pn = 0;
  
  for (int y = 0; y < n; y++)
    pn += paint4(0, y, 0, '.'), pn += paint4(m - 1, y, 0, '.');
  for (int x = 0; x < m; x++)
    pn += paint4(x, 0, 0, '.'), pn += paint4(x, n - 1, 0, '.');
  //printf("pn=%d\n", pn); print_flds();

  int tn = 1;
  while (pn < nm) {
    for (int y = 0; y < n; y++)
      for (int x = 0; x < m; x++)
	if (used[y][x] < 0) {
	  if (lines[y][x] == 'x') {
	    int aid = adj_ids(x, y);
	    if (aid >= 0) {
	      wis[tn] = paint(x, y, tn, 'x');
	      prts[tn] = aid;
	      chlds[aid].push_back(tn);
	      pn += wis[tn];
	      tn++;
	    }
	  }
	  else {
	    int aid = adj4_ids(x, y);
	    if (aid >= 0)
	      pn += paint4(x, y, aid, '.');
	  }
	}
    //printf("pn=%d\n", pn); print_flds();
  }
  //for (int i = 0; i < tn; i++) printf("%d ", prts[i]); putchar('\n');
  //for (int i = 0; i < tn; i++) printf("%d ", wis[i]); putchar('\n');
  //for (int i = 0; i < tn; i++) printf("%lu ", chlds[i].size()); putchar('\n');

  rec(0);

  printf("%d\n", dp[0][0]);
  return 0;
}