using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Threading;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using static util;
using P = pair<int, int>;

class Program {
    static void Main(string[] args) {
        var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        var solver = new Solver(sw);
        // var t = new Thread(solver.solve, 1 << 28); // 256 MB
        // t.Start();
        // t.Join();
        solver.solve();
        sw.Flush();
    }
}

class Solver {
    StreamWriter sw;
    Scan sc;
    void Prt(string a) => sw.WriteLine(a);
    void Prt<T>(IEnumerable<T> a) => Prt(string.Join(" ", a));
    void Prt(params object[] a) => Prt(string.Join(" ", a));
    public Solver(StreamWriter sw) {
        this.sw = sw;
        this.sc = new Scan();
    }

    public void solve() {
        int h, w;
        sc.Multi(out h, out w);
        var s = new string[h];
        for (int i = 0; i < h; i++)
        {
            s[i] = sc.Str;
        }
        var mf = new MinCostFlow(h * w + 2);
        int S = h * w;
        int T = h * w + 1;
        int c = 0;
        for (int i = 0; i < h; i++)
        {
            for (int j = 0; j < w; j++)
            {
                if (s[i][j] == 'o')  {
                    mf.addEdge(S, i * w + j, 1, 0);
                    ++c;
                }
                if (s[i][j] != '#') {
                    mf.addEdge(i * w + j, T, 1, 0);
                }
                if (i + 1 < h && s[i][j] != '#' && s[i + 1][j] != '#') {
                    mf.addEdge(i * w + j, (i + 1) * w + j, M, -1);
                }
                if (j + 1 < w && s[i][j] != '#' && s[i][j + 1] != '#') {
                    mf.addEdge(i * w + j, i * w + j + 1, M, -1);
                }
            }
        }
        Prt(-mf.run(S, T, c));

    }
}

class pair<T, U> : IComparable<pair<T, U>> {
    public T v1;
    public U v2;
    public pair() : this(default(T), default(U)) {}
    public pair(T v1, U v2) { this.v1 = v1; this.v2 = v2; }
    public int CompareTo(pair<T, U> a) {
        int c = Comparer<T>.Default.Compare(v1, a.v1);
        return c != 0 ? c : Comparer<U>.Default.Compare(v2, a.v2);
    }
    public override string ToString() => v1 + " " + v2;
    public void Deconstruct(out T a, out U b) { a = v1; b = v2; }
}
static class util {
    public static readonly int M = 1000000007;
    // public static readonly int M = 998244353;
    public static readonly long LM = 1L << 60;
    public static readonly double eps = 1e-11;
    public static void DBG(string a) => Console.Error.WriteLine(a);
    public static void DBG<T>(IEnumerable<T> a) => DBG(string.Join(" ", a));
    public static void DBG(params object[] a) => DBG(string.Join(" ", a));
    public static void Assert(params bool[] conds) {
        if (conds.Any(x => !x)) throw new Exception();
    }
    public static pair<T, U> make_pair<T, U>(T v1, U v2) => new pair<T, U>(v1, v2);
    public static int CompareList<T>(IList<T> a, IList<T> b) where T : IComparable<T> {
        for (int i = 0; i < a.Count && i < b.Count; i++)
            if (a[i].CompareTo(b[i]) != 0) return a[i].CompareTo(b[i]);
        return a.Count.CompareTo(b.Count);
    }
    public static bool inside(int i, int j, int h, int w) => i >= 0 && i < h && j >= 0 && j < w;
    public static readonly int[] dd = { 0, 1, 0, -1 };
    // static readonly string dstring = "RDLU";
    public static IEnumerable<P> adjacents(int i, int j)
        => Enumerable.Range(0, dd.Length).Select(k => new P(i + dd[k], j + dd[k ^ 1]));
    public static IEnumerable<P> adjacents(int i, int j, int h, int w)
        => adjacents(i, j).Where(p => inside(p.v1, p.v2, h, w));
    public static IEnumerable<P> adjacents(this P p) => adjacents(p.v1, p.v2);
    public static IEnumerable<P> adjacents(this P p, int h, int w) => adjacents(p.v1, p.v2, h, w);
    public static IEnumerable<int> all_subset(this int p) {
        for (int i = 0; ; i = i - p & p) {
            yield return i;
            if (i == p) break;
        }
    }
    public static Dictionary<T, int> compress<T>(this IEnumerable<T> a)
        => a.Distinct().OrderBy(v => v).Select((v, i) => new { v, i }).ToDictionary(p => p.v, p => p.i);
    public static Dictionary<T, int> compress<T>(params IEnumerable<T>[] a) => compress(a.SelectMany(x => x));
    public static T[] inv<T>(this Dictionary<T, int> dic) {
        var res = new T[dic.Count];
        foreach (var item in dic) res[item.Value] = item.Key;
        return res;
    }
    public static void swap<T>(ref T a, ref T b) where T : struct { var t = a; a = b; b = t; }
    public static void swap<T>(this IList<T> a, int i, int j) where T : struct { var t = a[i]; a[i] = a[j]; a[j] = t; }
    public static T[] copy<T>(this IList<T> a) {
        var ret = new T[a.Count];
        for (int i = 0; i < a.Count; i++) ret[i] = a[i];
        return ret;
    }
}

class Scan {
    StreamReader sr;
    public Scan() { sr = new StreamReader(Console.OpenStandardInput()); }
    public Scan(string path) { sr = new StreamReader(path); }
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public string Str => ReadLine.Trim();
    public string ReadLine => sr.ReadLine();
    public pair<T, U> Pair<T, U>() {
        T a; U b;
        Multi(out a, out b);
        return new pair<T, U>(a, b);
    }
    public P P => Pair<int, int>();
    public int[] IntArr => StrArr.Select(int.Parse).ToArray();
    public long[] LongArr => StrArr.Select(long.Parse).ToArray();
    public double[] DoubleArr => StrArr.Select(double.Parse).ToArray();
    public string[] StrArr => Str.Split(new[]{' '}, StringSplitOptions.RemoveEmptyEntries);
    bool eq<T, U>() => typeof(T).Equals(typeof(U));
    T ct<T, U>(U a) => (T)Convert.ChangeType(a, typeof(T));
    T cv<T>(string s) => eq<T, int>()    ? ct<T, int>(int.Parse(s))
                       : eq<T, long>()   ? ct<T, long>(long.Parse(s))
                       : eq<T, double>() ? ct<T, double>(double.Parse(s))
                       : eq<T, char>()   ? ct<T, char>(s[0])
                                         : ct<T, string>(s);
    public void Multi<T>(out T a) => a = cv<T>(Str);
    public void Multi<T, U>(out T a, out U b) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]);
    }
    public void Multi<T, U, V>(out T a, out U b, out V c) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]);
    }
    public void Multi<T, U, V, W>(out T a, out U b, out V c, out W d) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<W>(ar[3]);
    }
    public void Multi<T, U, V, W, X>(out T a, out U b, out V c, out W d, out X e) {
        var ar = StrArr; a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<W>(ar[3]); e = cv<X>(ar[4]);
    }
}

class MinCostFlow {
    class edge {
        public int to, cap, rev;
        public long cost;
        public edge(int to, int cap, long cost, int rev) {
            this.to = to;
            this.cap = cap;
            this.cost = cost;
            this.rev = rev;
        }
    }
    int n;
    List<edge>[] g;

    public MinCostFlow(int n) {
        this.n = n;
        g = new List<edge>[n];
        for (int i = 0; i < n; i++)
            g[i] = new List<edge>();
    }
    public void addEdge(int from, int to, int cap, long cost) {
        g[from].Add(new edge(to, cap, cost, g[to].Count));
        g[to].Add(new edge(from, 0, -cost, g[from].Count - 1));
    }
    public long run(int s, int t, int f) {
        long res = 0;
        var h = new long[n];
        while (f > 0) {
            var q = new PriorityQueue<pair<long, int>>(){ rev = true };
            var dist = new long[n];
            var prevv = new int[n];
            var preve = new int[n];
            for (int i = 0; i < n; i++) dist[i] = util.LM;
            dist[s] = 0;
            q.Push(new pair<long, int>(0, s));
            while (q.Count > 0) {
                var p = q.Pop();
                int v = p.v2;
                if (dist[v] < p.v1) continue;
                for (int i = 0; i < g[v].Count; ++i) {
                    var e = g[v][i];
                    if (e.cap > 0 && dist[e.to] > dist[v] + e.cost + h[v] - h[e.to]) {
                        dist[e.to] = dist[v] + e.cost + h[v] - h[e.to];
                        prevv[e.to] = v;
                        preve[e.to] = i;
                        q.Push(new pair<long, int>(dist[e.to], e.to));
                    }
                }
            }
            if (dist[t] == util.LM) break;
            for (int v = 0; v < n; ++v) h[v] += dist[v];

            int d = f;
            for (int v = t; v != s; v = prevv[v]) d = Math.Min(d, g[prevv[v]][preve[v]].cap);

            f -= d;
            res += d * h[t];
            for (int v = t; v != s; v = prevv[v]) {
                var e = g[prevv[v]][preve[v]];
                e.cap -= d;
                g[v][e.rev].cap += d;
            }
        }
        return res;
    }
}

// the greatest element pops
class PriorityQueue<T> {
    List<T> buf;
    public bool rev = false;
    Func<int, int, int> cmp;
    public PriorityQueue() {
        buf = new List<T>();
        cmp = (i, j) => Comparer<T>.Default.Compare(buf[i], buf[j]) * (rev ? -1 : 1);
    }
    public PriorityQueue(Func<T, T, int> cmp) {
        buf = new List<T>();
        this.cmp = (i, j) => cmp(buf[i], buf[j]);
    }
    void swap(int i, int j) { var t = buf[i]; buf[i] = buf[j]; buf[j] = t; }
    public void Push(T elem) {
        int n = buf.Count;
        buf.Add(elem);
        while (n > 0) {
            int i = (n - 1) >> 1;
            if (cmp(n, i) <= 0) break;
            swap(i, n);
            n = i;
        }
    }
    public T Pop() {
        T ret = buf[0];
        int n = buf.Count - 1;
        buf[0] = buf[n];
        buf.RemoveAt(n);
        for (int i = 0, j; (j = (i << 1) | 1) < n; i = j) {
            if (j != n - 1 && cmp(j, j + 1) < 0) ++j;
            if (cmp(i, j) < 0) swap(i, j);
            else break;
        }
        return ret;
    }
    public T Top => buf[0];
    public int Count => buf.Count;
}


Measured memory_bytes: 41164