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

struct BipartiteMatching {
    int n, timestamp;
    vector<vector<int>> graph;
    vector<int> alive, used, match;
    BipartiteMatching(int n) : \
        n(n), timestamp(0), graph(n), alive(n, 1), used(n, 0), match(n, -1) { }
    void add_edge(int u, int v) {
        graph[u].emplace_back(v);
        graph[v].emplace_back(u);
    }
    bool dfs(int idx) {
        used[idx] = timestamp;
        for (int to: graph[idx]) if (alive[to]) {
            int to_match = match[to];
            if (to_match == -1 || (used[to_match] != timestamp && dfs(to_match))) {
                match[idx] = to;
                match[to] = idx;
                return true;
            }
        }
        return false;
    }
    int bipartite_matching() {
        int ret = 0;
        for (int i = 0; i < n; i++) if (alive[i]) {
            if (match[i] == -1) ++timestamp, ret += dfs(i);
        }
        return ret;
    }
    friend ostream& operator<<(ostream& os, BipartiteMatching& bm) {
        for (int i = 0; i < bm.n; i++) if (i < bm.match[i]) {
            os << i << " - " << bm.match[i] << endl;
        }
        return os;
    }
};

int main() {
    int h, w; cin >> h >> w;
    vector<string> s(h);
    for (auto &si: s) cin >> si;
    BipartiteMatching bm(h * w);
    auto idx = [&](int i, int j) { return i * w + j; };
    int dij[] = {0, 1, 0, -1, 0};
    vector<int> cnt(2);
    for (int i = 0; i < h; i++) for (int j = 0; j < w; j++) {
        if (s[i][j] == 'w') cnt[0]++;
        if (s[i][j] == 'b') cnt[1]++;
        if (s[i][j] == 'w') {
            for (int k = 0; k < 4; k++) {
                int ni = i + dij[k], nj = j + dij[k + 1];
                if (ni < 0 || ni >= h || nj < 0 || nj >= w) continue;
                if (s[ni][nj] == 'b') bm.add_edge(idx(i, j), idx(ni, nj));
            }
        }
    }
    int p100 = bm.bipartite_matching();
    cnt[0] -= p100, cnt[1] -= p100;
    int p10 = min(cnt[0], cnt[1]);
    cnt[0] -= p10, cnt[1] -= p10;
    cout << p100 * 100 + p10 * 10 + cnt[0] + cnt[1] << endl;
    return 0;
}