#include<iostream>
#include<vector>
#include<string>
#include<algorithm>	
#include<map>
#include<set>
#include<utility>
#include<cmath>
#include<cstring>
#include<queue>
#include<stack>
#include<cstdio>
#include<sstream>
#include<iomanip>
#include<assert.h>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define pb push_back
#define mt make_tuple
#define all(in) in.begin(),in.end()
#define shosu(x) fixed<<setprecision(x)
using namespace std;
//kaewasuretyuui
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vp;
typedef vector<vp> vvp;
typedef vector<string> vs;
typedef vector<double> vd;
typedef tuple<int,int,int> tp;
typedef vector<tp> vt;
typedef vector<vd> vvd;
typedef pair<int,pii> pip;
typedef vector<pip>vip;
const double PI=acos(-1);
const double EPS=1e-7;
const int inf=1e8;
const ll INF=1e16;
int dx[]={0,1,0,-1};
int dy[]={1,0,-1,0};
struct edge{int to,cap,rev;};//ikisaki youryou gyakuhen
class MF{//max flow
	public:
	int n;
	vector<vector<edge> >G;//[MAX];
	vector<bool>used;//[MAX];
	MF(int size){
		n=size;
		G=vector<vector<edge> >(n);
	}
	void add_edge(int from, int to, int cap){
		edge q={to,cap,int(G[to].size())};
		G[from].push_back(q);
		q={from,0,int(G[from].size()-1)};
		G[to].push_back(q);
	}
	int dfs(int v,int t, int f) {
		if(v==t)return f;
		used[v]=1;
		for(int i=0;i<G[v].size();i++){
			edge &e=G[v][i];
			if(used[e.to]||e.cap<=0) continue;
			int d =dfs(e.to,t,min(f,e.cap));
			if(d>0){
				e.cap-=d;
				G[e.to][e.rev].cap+=d;
				return d;
			}
		}
		return 0;
	}
	int mf(int s,int t) {//from s to t,ford_fulkerson
		int flow=0,f;
		while(1){
			used=vector<bool>(n,false);
			f=dfs(s,t,inf);
			if(f==0)return flow;
			flow+=f;
		}
	}
};
int main(){
	int n,m;
	cin>>n>>m;
	vs in(n);
	rep(i,n)cin>>in[i];
	MF mf(2+n*m);
	rep(i,n)rep(j,m)if((i+j)%2==0)mf.add_edge(n*m,i*m+j,1);
	else mf.add_edge(i*m+j,n*m+1,1);
	rep(i,n)rep(j,m)if((i+j)%2==0&&in[i][j]!='.'){
		rep(k,4){
			int x=i+dx[k];
			int y=j+dy[k];
			if(x<0||y<0||x>=n||y>=m)continue;
			if(in[x][y]=='.')continue;
			mf.add_edge(i*m+j,x*m+y,1);
		}
	}
	int c=mf.mf(n*m,n*m+1);
	int coa=0,cob=0;
	rep(i,n)rep(j,m)if(in[i][j]=='w')coa++;
	else if(in[i][j]=='b')cob++;
	int out=c*100;
	coa-=c;cob-=c;
	out+=min(coa,cob)*10;
	out+=abs(coa-cob);
	cout<<out<<endl;
}