#include "bits/stdc++.h"
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
 
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
 
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
 
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template<class T> using pq = priority_queue<T>;
template<class T> using pqg = priority_queue<T, vector<T>, greater<T>>;
 
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define trav(a,x) for (auto& a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
 
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define ins insert

template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef DEBUG
#define dbg(x...) cerr << "\e[91m"<<__func__<<":"<<__LINE__<<" [" << #x << "] = ["; _print(x); cerr << "\e[39m" << endl;
#else
#define dbg(x...)
#endif


const int MOD = 1000000007;
const char nl = '\n';
const int MX = 100001; 

struct Edge {
    int v, u; ll cap, flow = 0;
    Edge(int v, int u, ll cap) : v(v), u(u),cap(cap) {}
};

struct Dinic {
    const ll flow_inf = 1e18;
    vector<Edge> edges;
    vector<vi> adj;
    int n, m = 0;
    int s, t; 
    vi level, ptr;
    queue<int> q;
    Dinic(int n, int s, int t) : n(n), s(s), t(t) {
        adj.resize(n); level.resize(n); ptr.resize(n);
    }

    void add_edge(int v, int u, ll cap) {
        edges.emplace_back(v, u, cap);
        edges.emplace_back(u, v, 0);
        adj[v].pb(m); adj[u].pb(m+1); m += 2;
    }

    bool bfs() {
        while (!q.empty()) {
            int v = q.front(); q.pop();
            trav(id, adj[v]) {
                if (edges[id].cap - edges[id].flow < 1) {
                    continue;
                }
                if (level[edges[id].u] != -1) continue;
                level[edges[id].u] = level[v] + 1;
                q.push(edges[id].u);
            }
        }
        return level[t] != -1;
    }

    ll dfs(int v, ll pushed) {
        if (pushed == 0) return 0;
        if (v == t) return pushed;
        for (int& cid = ptr[v]; cid < (int)adj[v].size(); cid++) {
            int id = adj[v][cid];
            int u = edges[id].u;
            if (level[v] + 1 != level[u] || edges[id].cap - edges[id].flow < 1) continue;
            ll tr = dfs(u, min(pushed, edges[id].cap - edges[id].flow));
            if (tr == 0) continue;
            edges[id].flow += tr;
            edges[id^1].flow -= tr;
            return tr;
        }
        return 0;
    }

    ll flow() {
        ll f = 0;
        while (true) {
            fill(level.begin(), level.end(), -1);
            level[s] = 0;
            q.push(s);
            if (!bfs()) break;
            fill(ptr.begin(), ptr.end(), 0);
            while (ll pushed = dfs(s, flow_inf)) f += pushed;
        }
        return f;
    }
};

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};
int N, M;
bool valid(int i, int j) { return i >= 0 && i < N && j >= 0 && j < M; }

void solve() {
    cin >> N >> M;
    string S[N]; F0R(i, N) cin >> S[i];
    ll ans = 0;
    F0R(i, N) F0R(j, M) ans += (S[i][j] == '.');
    ans /= 2;
    if (ans * (ans-1) > 1000000) {
        cout << 1000000 << nl; return;
    }
    ans = ans * (ans-1) + ans * ans;
    Dinic din(N*M+2, N*M, N*M+1);
    F0R(i, N) {
        F0R(j, M) {
            if ((i+j)%2) { 
                din.add_edge(i*M+j, N*M+1, 1);
            } else {
                din.add_edge(N*M, i*M+j, 1);
            }
        }
    }

    F0R(i, N) {
        F0R(j, M) {
            if ((i+j)%2 == 0) {
                if (S[i][j] == '#') continue;
                F0R(k, 4) {
                    int x = i + dx[k], y = j + dy[k];
                    if (valid(x, y) && S[x][y] == '.') {
                        din.add_edge(i*M+j, x*M+y, 1);
                    }
                }
            }
        }
    }
    din.flow();
    map<int, int> vs;
    F0R(i, N) {
        F0R(j, M) {
            if ((i+j)%2 && S[i][j] == '.') {
                vs[i*M+j] = sz(vs);
            }
        }
    }

    int match[N][M];
    F0R(i, N) {
        F0R(j, M) {
            match[i][j] = -1;
        }
    }

    trav(a, din.edges) {
        if (a.v < N*M && a.u < N*M && a.flow == 1) {
            match[a.v/M][a.v%M] = vs[a.u];
        }
    }

    /*F0R(i, N) {
        F0R(j, M) {
            cout << match[i][j] << " ";
        }
        cout << endl;
    }*/
    //dbg(vs);

    vector<vi> graph(sz(vs));
    trav(a, vs) {
        int x = a.f/M, y = a.f%M;
        F0R(i, 4) {
            int nx = x + dx[i], ny = y + dy[i];
            if (valid(nx, ny) && S[nx][ny] == '.') {
                graph[a.s].pb(match[nx][ny]);
            }
        }
    }

    F0R(r, sz(vs)) {
        bool vis[sz(vs)]; F0R(i, sz(vs)) vis[i] = false;
        vis[r] = true; ans--;
        queue<int> q; q.push(r);
        while (!q.empty()) {
            int v = q.front(); q.pop();
            trav(a, graph[v]) {
                if (!vis[a]) {
                    vis[a] = true;  ans--;
                    q.push(a);
                }
            }
        }
    }

    cout << min(ans, (ll) 1000000) << nl;


}
 
int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);

    int T = 1;
//    cin >> T;
    while(T--) {
        solve();
    }

	return 0;
}