#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <cassert>
using namespace std;

#define GET_ARG(a,b,c,F,...) F
#define REP3(i,s,e) for (i = s; i <= e; i++)
#define REP2(i,n) REP3 (i,0,(int)(n)-1)
#define REP(...) GET_ARG (__VA_ARGS__,REP3,REP2) (__VA_ARGS__)
#define RREP3(i,s,e) for (i = s; i >= e; i--)
#define RREP2(i,n) RREP3 (i,(int)(n)-1,0)
#define RREP(...) GET_ARG (__VA_ARGS__,RREP3,RREP2) (__VA_ARGS__)
#define DEBUG(x) cerr << #x ": " << x << endl

struct Edge {
    int to;
    int cap;
    int rev;
};

string s[50];
vector<Edge> e[2502];
bool used[2502];
int dx[] = {0,1,0,-1};
int dy[] = {1,0,-1,0};

void add_edge(int a, int b) {
    e[a].push_back({b,1,(int)e[b].size()});
    e[b].push_back({a,0,(int)e[a].size()-1});
}

int dfs(int v, int t, int f) {
    if (v == t) return f;
    used[v] = true;
    for (auto& x: e[v]) if (!used[x.to] && x.cap) {
        int d = dfs(x.to,t,min(f,x.cap));
        if (d > 0) {
            x.cap -= d;
            e[x.to][x.rev].cap += d;
            return d;
        }
    }
    return 0;
}

int main(void) {
    int i, j, k, n, m;
    cin >> n >> m;
    REP (i,n) cin >> s[i];
    int w = 0, b = 0;
    REP (i,n) REP (j,m) {
        if (s[i][j] == 'w') {
            add_edge(n*m,i*m+j);
            REP (k,4) {
                int ni = i + dx[k];
                int nj = j + dy[k];
                if (ni < 0 || ni >= n || nj < 0 || nj >= m) continue;
                add_edge(i*m+j,ni*m+nj);
            }
            w++;
        }
        else if (s[i][j] == 'b') {
            add_edge(i*m+j,n*m+1);
            b++;
        }
    }
    int ans = 0;
    for (;;) {
        REP (i,n*m+2) used[i] = false;
        int f = dfs(n*m,n*m+1,1);
        if (f == 0) break;
        ans += 100;
        w--; b--;
    }
    ans += min(w,b) * 10;
    ans += max(w,b) - min(w,b);
    cout << ans << endl;
    return 0;
}