#include <iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<map>
#include<set>
#include<stack>
#include<queue>
#include<math.h>
#include <cstring>
using namespace std;
typedef long long ll;
#define int long long
typedef vector<int> VI;
typedef pair<int, int> pii;
typedef vector<pii> VP;
typedef vector<string> VS;
typedef priority_queue<int> PQ;
template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b < a) { a = b; return 1; } return 0; }
#define fore(i,a) for(auto &i:a)
#define REP(i,n) for(int i=0;i<n;i++)
#define eREP(i,n) for(int i=0;i<=n;i++)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define eFOR(i,a,b) for(int i=(a);i<=(b);++i)
#define SORT(c) sort((c).begin(),(c).end())
#define rSORT(c) sort((c).rbegin(),(c).rend())
#define LB(x,a) lower_bound((x).begin(),(x).end(),(a))
#define UB(x,a) upper_bound((x).begin(),(x).end(),(a))
#define INF 1000000000
#define LLINF 9223372036854775807
#define mod 1000000007
//priority_queue<int,vector<int>, greater<int> > q2;

VI G[5000];

int match[5010];
bool used[5010];
int N;

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

int solve() {
	int res = 0;
	memset(match, -1, sizeof(match));
	REP(v, N) {
		if (match[v] < 0) {
			memset(used, 0, sizeof(used));
			if (dfs(v))res++;
		}
	}

	return res;
}

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int H, W; cin >> H >> W;
	VS S(H);
	REP(i, H)cin >> S[i];
	N = H * W;
	map<pii, int>mp;
	int w = 0, b = 0;
	int k = 0;
	REP(i, H)REP(j, W)mp[pii(i,j)] = k++;

	int dx[] = { 0,0,-1,1 };
	int dy[] = { -1,1,0,0 };

	REP(i, H) {
		REP(j, W) {
			if (S[i][j] == 'w')w++;
			if (S[i][j] == 'b')b++;
			REP(k, 4) {
				int nx = i + dx[k], ny = j + dy[k];
				if (nx >= 0 && nx < H&&ny >= 0 && ny < W) {
					if (S[i][j] != S[nx][ny] && S[i][j] != '.' && S[nx][ny] != '.') {
						G[mp[pii(i, j)]].push_back(mp[pii(nx, ny)]);
					}
				}
			}
		}
	}




	int ans = solve() * 100;
	
	w -= ans / 100;
	b -= ans / 100;
	ans += min(w, b) * 10;
	ans += abs(w - b);
	
	cout << ans << endl;




	return 0;
}