using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
using System.Diagnostics;
using System.Numerics;
using static System.Console;
using static System.Convert;
using static System.Math;
using static Template;
using Pi = Pair<int, int>;

class Solver
{
    public void Solve(Scanner sc)
    {

        int n, m;
        sc.Make(out n, out m);
        var grid = sc.Grid(n);
        var gh = new[] { 0, 0, 1, -1 };
        var gw = new[] { 1, -1, 0, 0 };
        var f = new Dinic(n * m + 2);
        var ctw = 0;
        var ctb = 0;
        for (var i = 0; i < n; i++)
            for (var j = 0; j < m; j++)
                if (grid[i][j] != '.')
                {
                    if ((i + j) % 2 == 0) ctw++;
                    else { ctb++; continue; }
                    for (var k = 0; k < 4; k++)
                    {
                        var h = gh[k] + i;
                        var w = gw[k] + j;
                        if (!Inside(h, w, n, m) || grid[h][w] == '.') continue;
                        f.AddEdge(i * m + j, h * m + w, 1);
                    }
                }
        for (var i = 0; i < n; i++)
            for (var j = 0; j < m; j++)
                if (grid[i][j] != '.')
                {
                    if ((i + j) % 2 == 0)
                        f.AddEdge(n * m, i * m + j, 1);
                    else f.AddEdge(i * m + j, n * m + 1, 1);
                }
        var c = f.Execute(n * m, n * m + 1);
        ctw -= c;
        ctb -= c;
        WriteLine(100 * c + 10 * Min(ctw, ctb) + Abs(ctw - ctb));
    }
    int[] gh = new[] { 0, 0, 1, -1 }, gw = new[] { 1, -1, 0, 0 };
    public static bool Inside(int h, int w, int H, int W)
        => 0 <= h && h < H && 0 <= w && w < W;
}

class Dinic
{
    List<Edge>[] G;
    int[] mincost, iter;
    public Dinic(int V)
    {
        G = Create(V, () => new List<Edge>());
    }
    public void AddEdge(int from, int to, int cap, int idx = -1)
    {
        G[from].Add(new Edge(to, cap, G[to].Count, false, idx));
        G[to].Add(new Edge(from, 0, G[from].Count - 1, true, idx));
    }
    bool ExistAugmentingPath(int s, int t)
    {
        mincost = Create(G.Length, () => -1);
        var Q = new Queue<int>();
        mincost[s] = 0;
        Q.Enqueue(s);
        while (Q.Any() && mincost[t] == -1)
        {
            var p = Q.Dequeue();
            foreach (var e in G[p])
                if (e.cap > 0 && mincost[e.to] == -1)
                {
                    mincost[e.to] = mincost[p] + 1;
                    Q.Enqueue(e.to);
                }
        }
        return mincost[t] != -1;
    }
    int FindBottleneck(int idx, ref int t, int flow)
    {
        if (idx == t) return flow;
        for (int i = iter[idx]; i < G[idx].Count; i++)
        {
            var eg = G[idx][i];
            if (eg.cap > 0 && mincost[idx] < mincost[eg.to])
            {
                var d = FindBottleneck(eg.to, ref t, Min(flow, eg.cap));
                if (d > 0)
                {
                    eg.cap -= d;
                    G[eg.to][eg.rev].cap += d;
                    return d;
                }
            }
        }
        return 0;
    }
    public int Execute(int s, int t)
    {
        int flow = 0;
        while (ExistAugmentingPath(s, t))
        {

            iter = new int[G.Length];
            int f = 0;
            while ((f = FindBottleneck(s, ref t, int.MaxValue)) > 0) flow += f;
        }
        return flow;
    }
    class Edge
    {
        public int to, rev, idx;
        public bool isrev;
        public int cap;
        public Edge(int t, int c, int r, bool ir, int i)
        {
            to = t; cap = c; rev = r; isrev = ir; idx = i;
        }
    }
}
#region Template
public static class Template
{
    static void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver().Solve(new Scanner());
        Console.Out.Flush();
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) > 0) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T a, ref T b) { var t = b; b = a; a = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(this IList<T> A, int i, int j) { var t = A[i]; A[i] = A[j]; A[j] = t; }
    public static T[] Create<T>(int n, Func<T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(); return rt; }
    public static T[] Create<T>(int n, Func<int, T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(i); return rt; }
    public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> A) => A.OrderBy(v => Guid.NewGuid());
    public static int CompareTo<T>(this T[] A, T[] B, Comparison<T> cmp = null) { cmp = cmp ?? Comparer<T>.Default.Compare; for (var i = 0; i < Min(A.Length, B.Length); i++) { int c = cmp(A[i], B[i]); if (c > 0) return 1; else if (c < 0) return -1; } if (A.Length == B.Length) return 0; if (A.Length > B.Length) return 1; else return -1; }
    public static int MaxElement<T>(this IList<T> A, Comparison<T> cmp = null) { cmp = cmp ?? Comparer<T>.Default.Compare; T max = A[0]; int rt = 0; for (int i = 1; i < A.Count; i++) if (cmp(max, A[i]) < 0) { max = A[i]; rt = i; } return rt; }
    public static T PopBack<T>(this List<T> A) { var v = A[A.Count - 1]; A.RemoveAt(A.Count - 1); return v; }
    public static void Fail<T>(T s) { Console.WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
}
public class Scanner
{
    public string Str => Console.ReadLine().Trim();
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public int[] ArrInt => Str.Split(' ').Select(int.Parse).ToArray();
    public long[] ArrLong => Str.Split(' ').Select(long.Parse).ToArray();
    public char[][] Grid(int n) => Create(n, () => Str.ToCharArray());
    public int[] ArrInt1D(int n) => Create(n, () => Int);
    public long[] ArrLong1D(int n) => Create(n, () => Long);
    public int[][] ArrInt2D(int n) => Create(n, () => ArrInt);
    public long[][] ArrLong2D(int n) => Create(n, () => ArrLong);
    private Queue<string> q = new Queue<string>();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T Next<T>() { if (q.Count == 0) foreach (var item in Str.Split(' ')) q.Enqueue(item); return (T)Convert.ChangeType(q.Dequeue(), typeof(T)); }
    public void Make<T1>(out T1 v1) => v1 = Next<T1>();
    public void Make<T1, T2>(out T1 v1, out T2 v2) { v1 = Next<T1>(); v2 = Next<T2>(); }
    public void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3) { Make(out v1, out v2); v3 = Next<T3>(); }
    public void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4) { Make(out v1, out v2, out v3); v4 = Next<T4>(); }
    public void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5) { Make(out v1, out v2, out v3, out v4); v5 = Next<T5>(); }
    public void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6) { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next<T6>(); }
    public void Make<T1, T2, T3, T4, T5, T6, T7>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6, out T7 v7) { Make(out v1, out v2, out v3, out v4, out v5, out v6); v7 = Next<T7>(); }
    //public (T1, T2) Make<T1, T2>() { Make(out T1 v1, out T2 v2); return (v1, v2); }
    //public (T1, T2, T3) Make<T1, T2, T3>() { Make(out T1 v1, out T2 v2, out T3 v3); return (v1, v2, v3); }
    //public (T1, T2, T3, T4) Make<T1, T2, T3, T4>() { Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4); return (v1, v2, v3, v4); }
}
public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1;
    public T2 v2;
    public Pair() { }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1; this.v2 = v2; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public override string ToString() => $"{v1.ToString()} {v2.ToString()}";
    public void Deconstruct(out T1 a, out T2 b) { a = v1; b = v2; }
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3;
    public Pair() : base() { }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2)
    { this.v3 = v3; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public override string ToString() => $"{base.ToString()} {v3.ToString()}";
    public void Deconstruct(out T1 a, out T2 b, out T3 c) { Deconstruct(out a, out b); c = v3; }
}
#endregion