//#pragma GCC target("avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>

#define ll long long
#define ld long double

#define rep(i, n) for(ll i = 0; i < n; ++i)
#define rep2(i, a, b) for(ll i = a; i <= b; ++i)
#define rrep(i, a, b) for(ll i = a; i >= b; --i)

#define pii pair<int, int>
#define pll pair<ll, ll>

#define fi first
#define se second

#define pb push_back
#define eb emplace_back

#define vi vector<int>
#define vll vector<ll>
#define vpii vector<pii>
#define vpll vector<pll>

#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()

#define endl '\n'
using namespace std;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

//const int MOD=1000000007;
const int MOD=998244353;
const ll INF=9223372036854775807;
const int inf=2147483647;
const double PI=acos(-1);
int dx[8] = {1,0,-1,0,1,1,-1,-1};
int dy[8] = {0,1,0,-1,-1,1,1,-1};
 
const int MAX = 310000;
template< typename flow_t >
struct Dinic {
  const flow_t INF;

  struct edge {
    int to;
    flow_t cap;
    int rev;
    bool isrev;
    int idx;
  };

  vector< vector< edge > > graph;
  vector< int > min_cost, iter;

  Dinic(int V) : INF(numeric_limits< flow_t >::max()), graph(V) {}

  void add_edge(int from, int to, flow_t cap, int idx = -1) {
    graph[from].emplace_back((edge) {to, cap, (int) graph[to].size(), false, idx});
    graph[to].emplace_back((edge) {from, 0, (int) graph[from].size() - 1, true, idx});
  }

  bool bfs(int s, int t) {
    min_cost.assign(graph.size(), -1);
    queue< int > que;
    min_cost[s] = 0;
    que.push(s);
    while(!que.empty() && min_cost[t] == -1) {
      int p = que.front();
      que.pop();
      for(auto &e : graph[p]) {
        if(e.cap > 0 && min_cost[e.to] == -1) {
          min_cost[e.to] = min_cost[p] + 1;
          que.push(e.to);
        }
      }
    }
    return min_cost[t] != -1;
  }

  flow_t dfs(int idx, const int t, flow_t flow) {
    if(idx == t) return flow;
    for(int &i = iter[idx]; i < graph[idx].size(); i++) {
      edge &e = graph[idx][i];
      if(e.cap > 0 && min_cost[idx] < min_cost[e.to]) {
        flow_t d = dfs(e.to, t, min(flow, e.cap));
        if(d > 0) {
          e.cap -= d;
          graph[e.to][e.rev].cap += d;
          return d;
        }
      }
    }
    return 0;
  }

  flow_t max_flow(int s, int t) {
    flow_t flow = 0;
    while(bfs(s, t)) {
      iter.assign(graph.size(), 0);
      flow_t f = 0;
      while((f = dfs(s, t, INF)) > 0) flow += f;
    }
    return flow;
  }

  void output() {
    for(int i = 0; i < graph.size(); i++) {
      for(auto &e : graph[i]) {
        if(e.isrev) continue;
        auto &rev_e = graph[e.to][e.rev];
        cout << i << "->" << e.to << " (flow: " << rev_e.cap << "/" << e.cap + rev_e.cap << ")" << endl;
      }
    }
  }
};


signed main(){
  cin.tie(0);
  ios::sync_with_stdio(false); 
  
  int n, m;
  cin >> n >> m;
  vector<string> a(n);
  rep(i,n) cin >> a[i];
  
  Dinic<int> G(n*m+2);
  int s = n*m, t = n*m+1;
  rep(i,n)rep(j,m){
    if((i+j)%2 || a[i][j] == '.')continue;
    
    int u = i*m+j;
    int v;
    
    if(i && a[i-1][j] != '.'){
      v = (i-1)*m+j;
      G.add_edge(u,v,1);
    }
    if(j && a[i][j-1] != '.'){
      v = i*m+(j-1);
      G.add_edge(u,v,1);
    }
    if(i+1<n && a[i+1][j] != '.'){
      v = (i+1)*m+j;
      G.add_edge(u,v,1);
    }
    if(j+1<m && a[i][j+1] != '.'){
      v = i*m+(j+1);
      G.add_edge(u,v,1);
    }
  }
  
  int cntw = 0, cntb = 0;
  rep(i,n)rep(j,m){
    if(a[i][j] == '.')continue;
    int u = i*m+j;
    if((i+j)%2 == 0){
      G.add_edge(s,u,1);
      cntw++;
    }
    else{
      G.add_edge(u,t,1);
      cntb++;
    }
  }
  
  int mx = G.max_flow(s,t);
  cntw -= mx; cntb -= mx;
  int ans = 100*mx+ 10*min(cntw,cntb) + max(cntw,cntb) - min(cntw,cntb);
  cout << ans << endl;
  
  
  return 0;
}