# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
# include <tuple>
# include <unordered_map>
# include <numeric>
# include <complex>
# include <bitset>
# include <random>
# include <chrono>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
typedef pair<LL, LL> P;
constexpr int INF = 2000000000;
constexpr int HINF = INF / 2;
constexpr double DINF = 100000000000000000.0;
constexpr long long LINF = 9223372036854775807;
constexpr long long HLINF = 4500000000000000000;
const double PI = acos(-1);
int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
# define ALL(x)      (x).begin(),(x).end()
# define UNIQ(c)     (c).erase(unique(ALL((c))),(c).end())
# define mp          make_pair
# define eb          emplace_back
# define FOR(i,a,b)  for(int i=(a);i<(b);i++)
# define RFOR(i,a,b) for(int i=(a);i>=(b);i--)
# define REP(i,n)    FOR(i,0,n)
# define INIT        std::ios::sync_with_stdio(false);std::cin.tie(0)

struct edge { int to, cap, rev; };

const int MAX_SIZE = 12345;

vector<edge>G[MAX_SIZE];

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 });
}

bool used[MAX_SIZE];
int dfs(int p, int t, int f) {
	if (p == t)return f;
	used[p] = true;

	for (int i = 0; i < G[p].size(); i++) {
		edge &e = G[p][i];
		if (used[e.to] || e.cap == 0)continue;
		int _f = dfs(e.to, t, min(f, e.cap));
		if (_f) {
			e.cap -= _f;
			G[e.to][e.rev].cap += _f;
			return _f;
		}
	}

	return 0;
}

int max_flow(int s, int t) {
	int flow = 0;
	while (true) {
		fill_n(used, MAX_SIZE, false);
		int f = dfs(s, t, INF);
		if (f)flow += f;
		else return flow;
	}
}


int n, m;
string st[51];

int main() {
	cin >> n >> m;
	int s = 2 * n*m + 1, t = s + 1;
	int wcnt = 0, bcnt = 0;
	REP(i, n)cin >> st[i];
	REP(i, n)REP(j, m) {
		if (st[i][j] == 'w')wcnt++;
		if (st[i][j] == 'b')bcnt++;
		add_edge(s, i*m + j, 1);
		add_edge(n*m + i*m + j, t, 1);
		if (j) {
			if (st[i][j] == 'w'&&st[i][j - 1] == 'b') {
				add_edge(i*m + j, n*m + i*m + j - 1, 1);
			}
			if (st[i][j] == 'b'&&st[i][j - 1] == 'w') {
				add_edge(i*m + j - 1, n*m + i*m + j, 1);
			}
		}
		if (i) {
			if (st[i][j] == 'w'&&st[i - 1][j] == 'b') {
				add_edge(i*m + j, n*m + (i - 1)*m + j, 1);
			}
			if (st[i][j] == 'b'&&st[i - 1][j] == 'w') {
				add_edge((i - 1)*m + j, n*m + i*m + j, 1);
			}
		}
	}
	int num = max_flow(s, t);
	cout << num * 100 + min(wcnt - num, bcnt - num) * 10 + max(wcnt - num, bcnt - num) - min(wcnt - num, bcnt - num) << endl;
}