#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;
#define al(a) a.begin(), a.end()
#define ral(a) a.rbegin(), a.rend()
#define sz(a) (int)a.size()
#define db(a, b) cout << #a << ": " << a << " " << #b << ": " << b << endl;

#include <atcoder/all>
using namespace atcoder;

//{右,左,上,下}
const int dy[] = {0, 0, -1, 1}, dx[] = {1, -1, 0, 0};

int main() {
  int n, m;
  cin >> n >> m;
  vector<string> grid(n);
  for (int i = 0; i < n; ++i) { cin >> grid[i]; }

  int V = n * m;
  mf_graph<int> g(V + 2);
  int s = V, t = V + 1;

  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      if (grid[i][j] == '.') continue;
      int v = i * m + j;
      if ((i + j) % 2 == 0)
        g.add_edge(s, v, 1);
      else
        g.add_edge(v, t, 1);
    }
  }

  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      if ((i + j) % 2 || grid[i][j] == '.') continue;
      for (int k = 0; k < 4; ++k) {
        int ni = dy[k] + i, nj = dx[k] + j;
        if (ni < 0 || nj < 0 || ni >= n || nj >= m) continue;
        if (grid[ni][nj] == '.' || grid[i][j] == grid[ni][nj]) continue;
        int v0 = i * m + j;
        int v1 = ni * m + nj;
        g.add_edge(v0, v1, 1);
      }
    }
  }

  int maxFlow = g.flow(s, t);
  int B = 0, W = 0;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      if (grid[i][j] == 'b') B++;
      if (grid[i][j] == 'w') W++;
    }
  }
  B -= maxFlow;
  W -= maxFlow;

  int ans = maxFlow * 100 + min(B, W) * 10 + abs(B - W);
  cout << ans << endl;
  return 0;
}