#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
//---------------------------------------------------------------------------------------------------
struct BipartiteMatching {
    vector<vector<int>> E; int n, m; vector<int> match, dist;
    void init(int _n,int _m){n=_n,m=_m;E.resize(n+m+2);match.resize(n+m+2);dist.resize(n+m+2);}
    bool bfs() {
        queue<int> que;
        rep(i, 1, n + 1) {
            if (!match[i]) dist[i] = 0, que.push(i);
            else dist[i] = inf;
        }
        dist[0] = inf;
        while (!que.empty()) {
            int u = que.front(); que.pop();
            if (u) fore(v, E[u]) if (dist[match[v]] == inf) {
                dist[match[v]] = dist[u] + 1;
                que.push(match[v]);
            }
        }
        return (dist[0] != inf);
    }
    bool dfs(int u) {
        if (u) {
            fore(v, E[u]) if (dist[match[v]] == dist[u] + 1) if (dfs(match[v])) {
                match[v] = u; match[u] = v;
                return true;
            }
            dist[u] = inf;
            return false;
        }
        return true;
    }
    void add(int a, int b) { b += n; E[a + 1].push_back(b + 1); E[b + 1].push_back(a + 1); }
    int whois(int x) { return match[x + 1] - 1; }
    int solve() {
        rep(i, 0, n + m + 1) match[i] = 0;
        int res = 0;
        while (bfs()) rep(i, 1, n + 1) if (!match[i] && dfs(i)) res++;
        return res;
    }
};
/*---------------------------------------------------------------------------------------------------
　　　　　　　　　　　 ∧＿∧  
　　　　　 ∧＿∧ 　（´<_｀ ）　 Welcome to My Coding Space!
　　　　 （ ´_ゝ`）　/　 ⌒i     
　　　　／　　　＼　 　  |　|     
　　　 /　　 /￣￣￣￣/　　|  
　 ＿_(__ﾆつ/　    ＿/ .| .|＿＿＿＿  
　 　　　＼/＿＿＿＿/　（u　⊃  
---------------------------------------------------------------------------------------------------*/






int H, W;
string S[50];
int dx[4] = { 0, 1, 0, -1 };
int dy[4] = { -1, 0, 1, 0 };
//---------------------------------------------------------------------------------------------------
void _main() {
    cin >> H >> W;
    rep(i, 0, H) cin >> S[i];

    vector<int> b, w;
    rep(y, 0, H) rep(x, 0, W) {
        if (S[y][x] == 'b') b.push_back(y * W + x);
        if (S[y][x] == 'w') w.push_back(y * W + x);
    }
    sort(b.begin(), b.end());
    sort(w.begin(), w.end());

    BipartiteMatching bm;
    bm.init(b.size(), w.size());
    rep(y, 0, H) rep(x, 0, W) if(S[y][x] == 'b'){
        rep(i, 0, 4) {
            int xx = x + dx[i];
            int yy = y + dy[i];
            if (xx < 0 || W <= xx) continue;
            if (yy < 0 || H <= yy) continue;
            if (S[yy][xx] != 'w') continue;

            int bb = lower_bound(b.begin(), b.end(), y * W + x) - b.begin();
            int ww = lower_bound(w.begin(), w.end(), yy * W + xx) - w.begin();
            bm.add(bb, ww);
        }
    }

    int p100 = bm.solve();

    int rb = b.size() - p100;
    int rw = w.size() - p100;
    int p10 = min(rb, rw);

    int ans = 100 * p100 + 10 * p10 + (b.size() - p100 - p10) + (w.size() - p100 - p10);
    cout << ans << endl;
}