#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>

using namespace std;

struct edge{
	int to;
	int cap;
	int rev;
};

int Ford_Fulkerson_dfs(vector<vector<edge> > &G, int pos, int flow, vector<bool> &used, int t){
	if(pos == t){
		return flow;
	}else{
		used[pos] = true;
		for(int i=0; i<G[pos].size(); i++){
			if(!used[G[pos][i].to] && G[pos][i].cap >0){
				int myflow = Ford_Fulkerson_dfs(G, G[pos][i].to, min(flow, G[pos][i].cap), used, t);
				if(myflow > 0){
					G[pos][i].cap -= myflow;
					G[ G[pos][i].to ][ G[pos][i].rev ].cap += myflow;
					return myflow;
				}
			}
		}
		return 0;
	}
}

int Ford_Fulkerson(vector<vector<edge> > &G, int s, int t){
	const int INF = 100000000;
	int flow=0;
	for(;;){
		vector<bool> used(G.size(), false);
		int f = Ford_Fulkerson_dfs(G, s, INF, used, t);
		if(f==0) break;
		else flow += f;
	}
	return flow;
}

void add_edge(vector<vector<edge> > &G, int from, int to, int cap){
	G[from].push_back( (edge){to, cap, (int)G[to].size()} );
	G[to].push_back( (edge){from, 0, (int)G[from].size()-1} );
}

int main(){
	int n,m;
	cin >> n >> m;
	vector<string> v(n);
	for(int i=0; i<n; i++){
		cin >> v[i];
	}

	// s -> w -> b -> t
	vector< vector<edge> > G(n*m + 2);
	int s = n*m;
	int t = n*m+1;

	int cnt_w = 0;
	int cnt_b = 0;
	for(int i=0; i<n; i++){
		for(int j=0; j<m; j++){
			if(v[i][j] == 'w'){
				cnt_w++;
				add_edge(G, s, i*m + j, 1);
				
				if(j+1<m && v[i][j+1] == 'b'){
					add_edge(G, i*m + j, i*m + j+1, 1);
				}
				if(i+1<n && v[i+1][j] == 'b'){
					add_edge(G, i*m + j, (i+1)*m + j, 1);
				}
			}else if(v[i][j] == 'b'){
				cnt_b++;
				add_edge(G, i*m + j, t, 1);
				
				if(j+1<m && v[i][j+1] == 'w'){
					add_edge(G, i*m + j+1, i*m + j, 1);
				}
				if(i+1<n && v[i+1][j] == 'w'){
					add_edge(G, (i+1)*m + j, i*m + j, 1);
				}
			}
		}
	}
	int bw = Ford_Fulkerson(G, s,t);

	int ans = 0;
	
	ans += bw*100;
	ans += (min(cnt_w, cnt_b) - bw)*10;
	ans += max(cnt_w, cnt_b) - min(cnt_w, cnt_b);
	cout << ans << endl;
	return 0;
}