#include <algorithm>
#include <cstdio>
#include <ctype.h>
#include <functional>
#include <iostream>
#include <iomanip>
#include <cassert>
#include <cfloat>
#include <climits>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;
typedef vector<vector<int> > graph;
struct BGM {
	int L, R; //左右のノード数
	graph g;
	vector<int> r2l; //右->左への対応
	BGM(int L, int R) : L(L), R(R), g(L), r2l(R, -1) {}
	void add_edge(int l, int r) {
		g[l].push_back(r);
	}
	bool augment(int l, vector<bool>& visited) {
		if (l == -1) return true;
		if (visited[l]) return false;
		visited[l] = true;
		vector<int>& e = g[l];
		for (int i = 0; i < e.size(); i++) {
			int r = e[i];
			if (augment(r2l[r], visited)) {
				r2l[r] = l;
				return true;
			}
		}
		return false;
	}
	int match() {
		int cnt = 0;
		for (int l = 0; l < L; l++) {
			vector<bool> visited(L);
			if (augment(l, visited)) ++cnt;
		}
		return cnt;
	}
};

int main() {
	int N,M;
	cin >> N >> M;
	vector<string> S(N);
	int t[50][50];
	int b=0;
	int w=0;
	for (int i = 0; i < N; i++) {
		cin >> S[i];
	}
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < M; j++) {
			if (S[i][j] == 'b') {
				t[i][j] = b;
				b++;
			}else if (S[i][j] == 'w') {
				t[i][j] = w;
				w++;
			}
		}
	}

	BGM bgm(b, w);

	for (int i = 0; i < N; i++) {
		for (int j = 0; j < M; j++) {
			if (i < N - 1) {
				if (S[i][j] == 'b'&&S[i + 1][j] == 'w') {
					bgm.add_edge(t[i][j], t[i + 1][j]);
				}

				if (S[i][j] == 'w'&&S[i + 1][j] == 'b') {
					bgm.add_edge(t[i + 1][j], t[i][j]);
				}
			}
			if (j < M - 1) {
				if (S[i][j] == 'b'&&S[i][j + 1] == 'w') {
					bgm.add_edge(t[i][j], t[i][j + 1]);
				}
				if (S[i][j] == 'w'&&S[i][j + 1] == 'b') {
					bgm.add_edge(t[i][j + 1], t[i][j]);
				}
			}
		}
	}
	int a = bgm.match();
	b = b - a;
	w = w - a;
	int v = min(b, w);
	int r = b + w - 2 * v;
	cout << a * 100 + v * 10 + r << endl;
	
	return 0;
}