using System;
using System.Collections.Generic;
using System.Linq;

namespace No421{
    public class Program{
        public static void Main(string[] args){
            var sr = new StreamReader();
            //---------------------------------
            var H = sr.Next<int>();
            var W = sr.Next<int>();
            var S = sr.Next<string>(H);

            var dx = new[]{0, 1, 0, -1};
            var dy = new[]{1, 0, -1, 0};
            Func<int, int, bool> isInside = (x, y) => 0 <= x && x < W && 0 <= y && y < H;
            Func<int, int, int> hash = (x, y) => x + y * W + 1;

            var dinic = new Dinic(H * W + 2);
            for(var y = 0; y < H; y++){
                for(var x = 0; x < W; x++){
                    if((x + y) % 2 == 1){
                        if(S[y][x] != '.') dinic.AddEdge(hash(x, y), H * W + 1, 1);
                        continue;
                    }

                    if(S[y][x] != '.') dinic.AddEdge(0, hash(x, y), 1);
                    for(var i = 0; i < 4; i++){
                        var nx = x + dx[i];
                        var ny = y + dy[i];
                        if(isInside(nx, ny) && S[y][x] != '.' && S[ny][nx] != '.'){
                            dinic.AddEdge(hash(x, y), hash(nx, ny), 1);
                        }
                    }
                }
            }

            var w = S.Sum(s => s.Count(c => c == 'w'));
            var b = S.Sum(s => s.Count(c => c == 'b'));

            var m3 = dinic.MaxFlow(0, H * W + 1);
            var m2 = Math.Min(w, b) - m3;
            var m1 = Math.Max(w, b) - m3 - m2;

            Console.WriteLine(m1 + m2 * 10 + m3 * 100);
            //---------------------------------
        }
    }

    public class Dinic{//🐜P194
        public class Edge{
            public int To;
            public int Cap;
            public int Rev;
        }

        private readonly List<Edge>[] _adj;
        private readonly int[] _level;
        private readonly int[] _iter;

        public Dinic(int v){
            _adj = new List<Edge>[v];
            for(var i = 0; i < v; i++) _adj[i] = new List<Edge>();
            _level = new int[v];
            _iter = new int[v];
        }

        public void AddEdge(int from, int to, int cap){
            _adj[from].Add(new Edge{To = to, Cap = cap, Rev = _adj[to].Count});
            _adj[to].Add(new Edge{To = from, Cap = 0, Rev = _adj[from].Count - 1});
        }

        public int MaxFlow(int s, int t){
            var flow = 0;
            while(true){
                Bfs(s);
                if(_level[t] < 0) return flow;
                for(var i = 0; i < _iter.Length; i++) _iter[i] = 0;
                int f;
                while((f = Dfs(s, t, int.MaxValue)) > 0) flow += f;
            }
        }

        private void Bfs(int s){
            for(var i = 0; i < _level.Length; i++) _level[i] = -1;
            var que = new Queue<int>();
            _level[s] = 0;
            que.Enqueue(s);

            while(que.Count > 0){
                var v = que.Dequeue();
                for(var i = 0; i < _adj[v].Count; i++){
                    var e = _adj[v][i];
                    if(e.Cap > 0 && _level[e.To] < 0){
                        _level[e.To] = _level[v] + 1;
                        que.Enqueue(e.To);
                    }
                }
            }
        }

        private int Dfs(int v, int t, int f){
            if(v == t) return f;
            for(var i = _iter[v]; i < _adj[v].Count; i++){
                var e = _adj[v][i];
                if(e.Cap > 0 && _level[v] < _level[e.To]){
                    var d = Dfs(e.To, t, Math.Min(f, e.Cap));
                    if(d > 0){
                        e.Cap -= d;
                        _adj[e.To][e.Rev].Cap += d;
                        return d;
                    }
                }
            }
            return 0;
        }
    }

    public class StreamReader{
        private readonly char[] _c = {' '};
        private int _index = -1;
        private string[] _input = new string[0];
        private readonly System.IO.StreamReader _sr = new System.IO.StreamReader(Console.OpenStandardInput());

        public T Next<T>(){
            if(_index == _input.Length - 1){
                _index = -1;
                while(true){
                    string rl = _sr.ReadLine();
                    if(rl == null){
                        if(typeof(T).IsClass) return default(T);
                        return (T)typeof(T).GetField("MinValue").GetValue(null);
                    }
                    if(rl != ""){
                        _input = rl.Split(_c, StringSplitOptions.RemoveEmptyEntries);
                        break;
                    }
                }
            }
            return (T)Convert.ChangeType(_input[++_index], typeof(T), System.Globalization.CultureInfo.InvariantCulture);
        }

        public T[] Next<T>(int x){
            var ret = new T[x];
            for(var i = 0; i < x; ++i) ret[i] = Next<T>();
            return ret;
        }

        public T[][] Next<T>(int y, int x){
            var ret = new T[y][];
            for(var i = 0; i < y; ++i) ret[i] = Next<T>(x);
            return ret;
        }
    }
}