#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define mem(a) memset(a,0,sizeof(a))
#define pd(a) printf("%.10f\n",a)
#define pb(a) push_back(a)
#define in(a) insert(a)
#define pi M_PI
#define R cin>>
#define F first
#define S second
#define C class
#define ll long long
#define ln cout<<'\n'
template<C T>void pr(T a){cout<<a;ln;}
template<C T,C T2>void pr(T a,T2 b){cout<<a<<' '<<b;ln;}
template<C T,C T2,C T3>void pr(T a,T2 b,T3 c){cout<<a<<' '<<b<<' '<<c;ln;}
template<C T>void PR(T a,int n){rep(i,n){if(i)cout<<' ';cout<<a[i];}ln;}
bool check(int n,int m,int x,int y){return x>=0&&x<n&&y>=0&&y<m;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,1,0,-1};
typedef pair<int,int> P;
const int MAX_V=2555;

int u[55][55];
int n,m;
struct edge{
  int to,cap,rev;
};
vector<edge> G[MAX_V];
bool used[MAX_V];

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

int dfs(int v,int t,int f) {
  if(v==t) return f;
  used[v]=true;
  rep(i,G[v].size()) {
    edge &e=G[v][i];
    if(!used[e.to] && e.cap>0) {
      int d=dfs(e.to,t,min(f,e.cap));
      if(d>0) {
        e.cap-=d;
        G[e.to][e.rev].cap+=d;
        if(v<n*m) u[v/m][v%m]=1;
        if(e.to<n*m) u[e.to/m][e.to%m]=1;
        return d;
      }
    }
  }
  return 0;
}

int max_flow(int s,int t) {
  int flow=0;
  for(;;) {
    memset(used,0,sizeof(used));
    int f=dfs(s,t,MAX);
    if(!f)return flow;
    flow+=f;
  }
}

void Main() {
  cin >> n >> m;
  string s[n];
  rep(i,n) cin >> s[i];
  rep(i,n) {
    rep(j,m) {
      if(s[i][j]=='w') {
        rep(k,4) {
          int x=i+dx[k],y=j+dy[k];
          if(check(n,m,x,y)&&s[x][y]=='b') add_edge(i*m+j,x*m+y,1);
        }
        add_edge(2501,i*m+j,1);
      } else if(s[i][j]=='b') add_edge(i*m+j,2502,1);
    }
  }
  int ans=max_flow(2501,2502)*100;
  int x=0,y=0;
  rep(i,n) {
    rep(j,m) {
      if(!u[i][j]) {
        if(s[i][j]=='w') x++;
        if(s[i][j]=='b') y++;
      }
    }
  }
  ans+=min(x,y)*10;
  ans+=abs(x-y);
  pr(ans);
}

int main() {
  ios::sync_with_stdio(0);cin.tie(0);
  Main();return 0;
}