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

namespace No421_1{
    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;

            var bg = new BipartiteGraph(H * W);
            for(var y = 0; y < H; y++){
                for(var x = 0; x < W; x++){
                    if((x + y) % 2 == 0) continue;
                    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] != '.'){
                            bg.AddEdge(hash(x, y), hash(nx, ny));
                        }
                    }
                }
            }

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

            var m3 = bg.Matching();
            var m2 = Math.Min(w, b) - m3;
            var m1 = Math.Max(w, b) - m3 - m2;
            Console.WriteLine(m1 + m2 * 10 + m3 * 100);
            //---------------------------------
        }
    }

    public class BipartiteGraph{//🐜P197
        private readonly List<int>[] _adj;
        private readonly int[] _match;
        private readonly bool[] _used;
         
        public BipartiteGraph(int v){
            _adj = new List<int>[v];
            for(var i = 0; i < v; i++) _adj[i] = new List<int>();
            _match = new int[v];
            _used = new bool[v];
        }

        public void AddEdge(int u, int v){
            _adj[u].Add(v);
            _adj[v].Add(u);
        }

        public int Matching(){
            var res = 0;
            for(var i = 0; i < _match.Length; i++) _match[i] = -1;
            for(var v = 0; v < _match.Length; v++){
                if(_match[v] < 0){
                    for(var j = 0; j < _used.Length; j++) _used[j] = false;
                    if(Dfs(v)) res++;
                }
            }
            return res;
        }

        private bool Dfs(int v){
            _used[v] = true;
            for(var i = 0; i < _adj[v].Count; i++){
                var u = _adj[v][i];
                var w = _match[u];
                if(w < 0 || (!_used[w] && Dfs(w))){
                    _match[v] = u;
                    _match[u] = v;
                    return true;
                }
            }
            return false;
        }
    }

    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;
        }
    }
}