#include<bits/stdc++.h>

using namespace std;
typedef unsigned int uint;
typedef long long int ll;
typedef unsigned long long int ull;

#define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;
#define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;
#define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;}
#define debugaar(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}
#define ALL(v) (v).begin(),(v).end()
#define BIGINT 0x7FFFFFFF
#define E107 1000000007ll
void printbit(int u){if(u==0)cout<<0;else{int s=0,k=0;for(;0<u;u>>=1,k++)s=(s<<1)|(u&1);for(;0<k--;s>>=1)cout<<(s&1);}}

#define TIME chrono::system_clock::now()
#define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count())
namespace{
    std::chrono::system_clock::time_point t;
    void tic(){t=TIME;}
    void toc(){fprintf(stderr,"TIME : %lldms\n",MILLISEC(TIME-t));}
}

template<typename T1,typename T2>
ostream& operator <<(ostream &o,const pair<T1,T2> p){o<<"("<<p.first<<":"<<p.second<<")";return o;}


void safebreak(){static auto t = TIME;assert (MILLISEC(TIME-t) < 5000);}

// todo : typedef int_c int // capacity

// TODO:マーカーの実装？
class Flow{
public:
    size_t n;
    struct Arrow{
        int from,to;
        int w_max; // TODO: leftに改名
        int cap;
        
        Arrow(int from=0,int to=0,int w=1):from(from),to(to),w_max(w),cap(w){}
        bool operator<(const Arrow& a) const {return (from<a.from)|(to<a.to)|(w_max<a.w_max)|(cap<a.cap);}
    };
    vector<vector<int>> vertex_to;
    vector<vector<int>> vertex_from;
    vector<Arrow> arrow;
    
    Flow(int n,int m=5010):n(n),vertex_to(n),vertex_from(n){arrow.reserve(m);}
    
    void connect(int from, int to, int w_max){
        vertex_to[from].push_back(arrow.size()); // toto
        vertex_from[to].push_back(arrow.size()); // fromfrom
        arrow.emplace_back(from,to,w_max);
    }
    size_t degree(int v){
        return vertex_to[v].size() + vertex_from[v].size();
    }
    size_t degree_in(int v){
        return vertex_from[v].size();
    }
    size_t degree_out(int v){
        return vertex_to[v].size();
    }
};
// DAG
int _dinic_path_dfs(Flow& flow, vector<int>& result, vector<bool>& flag, const vector<int>& dist, int u, int i_sink, int mini){
    // TODO: 経路再利用
    if (i_sink == u) return mini;
    if (flag[u]) return -1;
    flag[u] = true;
    
    int sumw = 0;
    bool term=true;
    for (int e : flow.vertex_to[u]){
        Flow::Arrow& a = flow.arrow[e];
        if (a.w_max > 0 && dist[u]>dist[a.to]){
            int w ;
            if (mini < 0)
                w = a.w_max;
            else
                w = min(a.w_max, mini);
            
            w = _dinic_path_dfs(flow, result, flag, dist, a.to, i_sink, w);
            if (w==-1) continue;
            a.w_max -= w;
            result[a.to] += w;
            
            //printf("%d->%d (%d) : w=%d mini=%d \n",a.from,a.to,a.w_max+w,w,mini);
            
            sumw +=w;
            mini -=w;
            term = false;
            flag[u] = false;
        }
    }
    for (int e : flow.vertex_from[u]){
        Flow::Arrow& a = flow.arrow[e];
        if (a.cap>a.w_max && dist[u]>dist[a.from]){
            int w ;
            if (mini < 0)
                w = a.cap-a.w_max;
            else
                w = min(a.cap-a.w_max, mini);
            
            w = _dinic_path_dfs(flow, result, flag, dist, a.from, i_sink, w);
            if (w==-1) continue;
            a.w_max += w;
            result[a.to] -= w;
            
            //printf("%d<-%d (%d) : w=%d mini=%d \n",a.from,a.to,a.w_max-w,w,mini);
            
            sumw +=w;
            mini -=w;
            term = false;
            flag[u] = false;
        }
    }
    return term ? -1 : sumw;
}

// flowは書き換えられる．
void dinic(Flow &flow, vector<int>& result, int i_source, int i_sink){
    assert(i_source != i_sink);
    
    result.resize(flow.n);
    
    vector<int> dist(flow.n);
    queue<int> q;
    vector<bool> flag(flow.n); // TODO: 
    for (int distbegin=0; ; distbegin+=flow.n){
        safebreak();
        
        q.emplace(i_sink); // bfsはsinkからsourceへの距離を計算．
        dist[i_sink] = distbegin+1;
        while (!q.empty()){
            int v = q.front();
            q.pop();
            for (int ie : flow.vertex_from[v]){
                const Flow::Arrow& e = flow.arrow[ie];
                if (0<e.w_max && dist[e.from] <= distbegin){
                    dist[e.from] = dist[v]+1;
                    q.emplace(e.from);
                }
            }
            for (int ie : flow.vertex_to[v]){
                const Flow::Arrow& e = flow.arrow[ie];
                if (e.w_max<e.cap && dist[e.to] <= distbegin){
                    dist[e.to] = dist[v]+1;
                    q.emplace(e.to);
                }
            }
        }
        //debugv(dist);
        fill(ALL(flag),false);
        
        if (dist[i_source] <= distbegin){
            break;
        }else{
            result[i_source] += _dinic_path_dfs(flow,result,flag,dist,i_source,i_sink,-1);
        }
    }
    
}

class BipartiteMatching{
public:
    Flow flow;
    int n,m;
    int ss;

    BipartiteMatching(int n,int m):flow(2+n+m),n(n),m(m),ss(n+m){
        for (int i=0;i<n;i++)
            flow.connect(ss,i,1);
        for (int i=0;i<m;i++)
            flow.connect(n+i,ss+1,1);
    }
    
    void connect(int l,int r){
        flow.connect(l  ,r+n ,1);
    }

    void solve_dinic(set<Flow::Arrow>& result){
        vector<int> r;
        dinic(flow,r,ss,ss+1);
        
        for (Flow::Arrow& a : flow.arrow){
            if (a.from==ss || a.to==ss+1) continue;
            if (a.w_max == 0){
                result.insert(a);
            }
        }
    }
};


int width,height;
int m,n;

string cho[55];

int main(){
    int i,j,k;
    int x,y,a,b;
    
    cin >> height >> width;
    
    n = height*width;
    
    BipartiteMatching bm(n,n);
    
    for (y=0;y<height;y++){
        cin >> cho[y];
    }
    int white,black;
    white=black=0;
    for (y=0;y<height;y++){
        for (x=0;x<width;x++){
            if (cho[y][x]=='.') continue;
            if (cho[y][x]=='w')
                white++;
            else
                black++;
            if ((y^x)&1) continue;
            if (0 < x && cho[y][x-1]!='.')
                bm.connect(x+y*width,x-1+y*width);
            if (0 < y && cho[y-1][x]!='.')
                bm.connect(x+y*width,x+(y-1)*width);
            if (width-1 > x && cho[y][x+1]!='.')
                bm.connect(x+y*width,x+1+y*width);
            if (height-1 > y && cho[y+1][x]!='.')
                bm.connect(x+y*width,x+(y+1)*width);
            
        }
    }
    
    set<Flow::Arrow> pairs;
    
    bm.solve_dinic(pairs);
    
    int np = pairs.size();
    white -= np;
    black -= np;
    
    cout << ( (np*100) + (min(white,black)*10) + abs(white-black) ) << endl;
    
    
    return 0;
}