#include <iostream>
#include <vector>
#include <cstring>
using namespace std;

const int MAX_N = 60;

struct BipartiteMatching {
    int V;  // 頂点数
    vector<vector<int> > graph; // グラフの隣接リスト表現
    vector<int> match;  // 各頂点ごとのマッチングの対応
    vector<bool> used;  // DFSの際に使用

    BipartiteMatching(int v) {
        V = v;
        graph = vector<vector<int> >(V);
        match = vector<int>(V);
        used = vector<bool>(V);
    }

    // uとvを連結にする
    void AddEdge(int u, int v) {
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    bool DFS(int v) {
        used[v] = true;
        for (int i = 0; i < graph[v].size(); i++) {
            int u = graph[v][i], w = match[u];
            if (w < 0 || (!used[w] && DFS(w))) {
                match[v] = u;
                match[u] = v;
                return true;
            }
        }
        return false;
    }

    // 二部マッチングを解く
    int Solve() {
        int res = 0;
        fill(match.begin(), match.end(), -1);
        for (int v = 0; v < V; v++) {
            if (match[v] < 0) {
                fill(used.begin(), used.end(), false);
                if (DFS(v)) {
                    res++;
                }
            }
        }
        return res;
    }
};

int n, m;

int conv_id(int row, int col) {
    return row * m + col;
}

string s[MAX_N];

int main() {
    cin >> n >> m;

    BipartiteMatching bm(n * m);

    int w_num = 0, b_num = 0;
    for (int r = 0; r < n; r++) {
        cin >> s[r];

        for (int c = 0; c < m; c++) {
            if (s[r][c] == 'w') w_num++;
            else if (s[r][c] == 'b') b_num++;
        }
    }

    for (int r = 0; r < n; r++) {
        for (int c = 0; c < m; c++) {
            if (s[r][c] == 'w') {
                if (r - 1 >= 0 && s[r - 1][c] == 'b') {
                    bm.AddEdge(conv_id(r, c), conv_id(r - 1, c));
                }
                if (r + 1 < n && s[r + 1][c] == 'b') {
                    bm.AddEdge(conv_id(r, c), conv_id(r + 1, c));
                }
                if (c - 1 >= 0 && s[r][c - 1] == 'b') {
                    bm.AddEdge(conv_id(r, c), conv_id(r, c - 1));
                }
                if (c + 1 < m && s[r][c + 1] == 'b') {
                    bm.AddEdge(conv_id(r, c), conv_id(r, c + 1));
                }
            }
        }
    }

    int matching = bm.Solve(),
        score3 = matching * 100,
        score2 = min(w_num - matching, b_num - matching) * 10,
        score1 = (w_num + b_num) - matching * 2 - score2 / 10 * 2;
    cout << score1 + score2 + score3 << endl;
    /*
    cout << "w: " << w_num << " " << "b: " << b_num << endl;
    cout << score1 << " " << score2 << " " << score3 << endl;
    */

    return 0;
}