#include<bits/stdc++.h>

using namespace std;

struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}init;


struct edge{
    int flow,to,rev;
};
typedef vector<edge> E;
typedef vector<E> Graph;

vector<int> bfs(Graph& G,int s){
    int N = G.size();
    queue<int> que;
    vector<int> dist(N,-1);
    dist[s] = 0;
    que.push(s);
    for(;!que.empty();que.pop()){
        auto v=que.front();
        for(auto& e : G[v])
            if(e.flow>0&&dist[e.to]==-1){
                dist[e.to] = dist[v] + 1;
                que.push(e.to);
        }
    }
    return dist;
}

int maxflow(Graph& G,int s,int t){
    int res=0;
    int N = G.size();
    while(true){
        auto dist = bfs(G,s);
        if(dist[t] < 0)break;
        vector<unsigned> iter(N,0);
        std::function<int(int,int)> dfs=[&](int v,int f){
            if(v==s)return f;
            for(auto &i = iter[v]; i < G[v].size(); i++){
                edge &e = G[v][i];
                edge &re = G[e.to][e.rev];
                if(re.flow>0 && dist[v] >dist[e.to]){
                    int d=dfs(e.to,min(f,re.flow));
                    if(d>0){e.flow+=d;re.flow-=d;return d;}
                }
            }
            return 0;
        };
        int f;
        while((f=dfs(t,114514))> 0)res+=f;
    }
    return res;
}

void addedge(Graph& g,int a,int b,int f){
    int c=g[a].size();
    int d=g[b].size();
    g[a].push_back(edge{f,b,d});
    g[b].push_back(edge{0,a,c});
}

typedef vector<int> V;
typedef vector<V> VV;
int main(){
    int R,C;
    cin>>R>>C;
    vector<string> choko(R);
    for(auto &s:choko)cin>>s;
    int B=0,W=0;
    int S=0;
    int G=1;
    VV id(R,V(C));
    int cnt=2;
    for(auto &v:id)for(auto &u:v)u=cnt++;
    Graph g(cnt);
    for(int r=0;r<R;r++)
        for(int c=0;c<C;c++){
            if(choko[r][c]=='b'){
                addedge(g,S,id[r][c],1);
                if(c+1<C)addedge(g,id[r][c],id[r][c+1],1);
                if(r+1<R)addedge(g,id[r][c],id[r+1][c],1);
                B++;
            }
            if(choko[r][c]=='w'){
                addedge(g,id[r][c],G,1); 
                if(c+1<C)addedge(g,id[r][c+1],id[r][c],1);
                if(r+1<R)addedge(g,id[r+1][c],id[r][c],1);
                W++;
            }
        }
    
    int f=maxflow(g,S,G);
    int k=min(B-f,W-f);
    cout<<100*f+10*k+B+W-(f+k)*2<<endl;
    return 0;
}