#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<numeric>
#include<cmath>
#include<utility>
#include<tuple>
#include<cstdint>
#include<cstdio>
#include<iomanip>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<deque>
#include<unordered_map>
#include<unordered_set>
#include<bitset>
#include<cctype>
#include<chrono>
#include<random>
#include<cassert>
#include<cstddef>
#include<iterator>
#include<string_view>
#include<type_traits>

#ifdef LOCAL
#  include "debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)
#define rrep(i,n) for(int i=(n)-1; i>=0; i--)
#define FOR(i,a,b) for(int i=(a); i<(b); i++)
#define RFOR(i,a,b) for(int i=(b-1); i>=(a); i--)
#define ALL(v) v.begin(), v.end()
#define RALL(v) v.rbegin(), v.rend()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define pb push_back
using ll = long long;
using D = double;
using LD = long double;
using P = pair<int, int>;
template<typename T> using PQ = priority_queue<T,vector<T>>;
template<typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
void yesno(bool flag) {cout << (flag?"Yes":"No") << "\n";}

template<typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << p.first << " " << p.second;
    return os;
}
template<typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
    is >> p.first >> p.second;
    return is;
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    int s = (int)v.size();
    for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
    return os;
}
template<typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for (auto &x : v) is >> x;
    return is;
}
void in() {}
template<typename T, class... U>
void in(T &t, U &...u) {
    cin >> t;
    in(u...);
}
void out() { cout << "\n"; }
template<typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u) {
    cout << t;
    if (sizeof...(u)) cout << sep;
    out(u...);
}
void outr() {}
template<typename T, class... U, char sep = ' '>
void outr(const T &t, const U &...u) {
    cout << t;
    outr(u...);
}

#include "atcoder/maxflow.hpp"

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

constexpr ll inf = 1e12;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int h,w; in(h,w);
    int n = (h-2)*(w-2);
    atcoder::mf_graph<ll> g(n*2);
    FOR(i,1,n-1) g.add_edge(i,i+n,1);

    vector<string> s(h); in(s);
    FOR(i,1,h-1)FOR(j,1,w-1){
        int ok1 = 1;
        FOR(di,-1,2)FOR(dj,-1,2) if(s[i+di][j+dj] == '#') ok1 = 0;
        rep(k,8){
            int ni = i+dx[k], nj = j+dy[k];
            if(ni < 1 or nj < 1 or ni >= h-1 or nj >= w-1) continue;
            int ok2 = 1;
            FOR(di,-1,2)FOR(dj,-1,2) {
                if(s[ni+di][nj+dj] == '#') ok2 = 0;
            }
            if(ok1 and ok2) {
                int a = (i-1)*(w-2)+(j-1);
                int b = (ni-1)*(w-2)+(nj-1);
                g.add_edge(a+n,b, inf);
                g.add_edge(b+n,a, inf);
            }
        }
    }
    out(g.flow(0+n, n-1));
}