#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




#define INF INT_MAX/2
struct Maxflow {
	struct edge { int to, cap, rev; edge(int t, int c, int r) { to = t; cap = c; rev = r; } };
	int V;
	vector<vector<edge>> G;
	vector<int> itr, level;

	Maxflow(int V) : V(V) { G.assign(V, vector<edge>()); }

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

	void bfs(int s) {
		level.assign(V, -1);
		queue<int> q;
		level[s] = 0; q.push(s);
		while (!q.empty()) {
			int v = q.front(); q.pop();
			for (auto &e : G[v]) {
				if (e.cap > 0 and level[e.to] < 0) {
					level[e.to] = level[v] + 1;
					q.push(e.to);
				}
			}
		}
	}

	int dfs(int v, int t, int f) {
		if (v == t) return f;
		for (int& i = itr[v]; i < (int)G[v].size(); ++i) {
			edge& e = G[v][i];
			if (e.cap > 0 and level[v] < level[e.to]) {
				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 run(int s, int t) {
		int ret = 0, f;
		while (bfs(s), level[t] >= 0) {
			itr.assign(V, 0);
			while ((f = dfs(s, t, INF)) > 0) ret += f;
		}
		return ret;
	}
};
//-----------------------------------------------------------------
int N, M;
string S[50];
int idx[50][50];
int dx[2] = { 1, 0 };
int dy[2] = { 0, 1 };
//-----------------------------------------------------------------
int main() {
	cin >> N >> M;
	rep(i, 0, N) cin >> S[i];

	int b = 0, w = 0;
	rep(y, 0, N) rep(x, 0, M) {
		if (S[y][x] == 'w')
			idx[y][x] = w, w++;
		else if (S[y][x] == 'b')
			idx[y][x] = b, b++;
	}

	Maxflow mf(1 + w + b + 1);
	rep(i, 0, w) mf.add_edge(0, i + 1, 1);
	rep(y, 0, N) rep(x, 0, M) if(S[y][x] != '.') rep(i, 0, 2) {
		int yy = y + dy[i];
		int xx = x + dx[i];
		if (yy < 0 || N <= yy) continue;
		if (xx < 0 || M <= xx) continue;
		if (S[yy][xx] == '.') continue;

		int bb = (S[y][x] == 'b' ? idx[y][x] : idx[yy][xx]);
		int ww = (S[y][x] == 'b' ? idx[yy][xx] : idx[y][x]);
		mf.add_edge(ww + 1, bb + 1 + w, 1);
	}
	rep(i, 0, b) mf.add_edge(1 + w + i, 1 + w + b, 1);

	int m = mf.run(0, 1 + w + b);

	int ans = 0;
	ans += m * 100;
	ans += min(b - m, w - m) * 10;
	ans += abs(b - w);

	cout << ans << endl;
}