#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

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

template<typename flow_t>
struct Dinic{
    const flow_t INF;

    struct Edge{
        int to;
        flow_t cap;
        int rev;
        bool isrev;
        Edge(int to, flow_t cap, int rev, bool isrev) : to(to), cap(cap), rev(rev), isrev(isrev) {}
    };

    vector<vector<Edge>> graph;
    vector<int> min_cost;       // sからの距離(bfsで調べる)
    vector<int> iter;           // どこまで調べ終わったか(dfs時に使用)

    Dinic(int V) : INF(numeric_limits<flow_t>::max() / 2){
        graph.resize(V);
    }

    void add_edge(int from, int to, flow_t cap){
        graph[from].push_back(Edge(to, cap, graph[to].size(), false));
        graph[to].push_back(Edge(from, 0, graph[from].size() - 1, true));
    }

    // 最短路探索
    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 v, int t, flow_t flow){
        if(v == t)  return flow;
        for(int &i = iter[v]; i < (int)graph[v].size(); ++i){
            Edge &e = graph[v][i];
            if(e.cap > 0 && min_cost[v] < 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;
        // 最短路を求めて、そのパスに最大流を流す
        while(bfs(s, t)){
            iter.assign(graph.size(), 0);
            flow_t f = 0;
            while((f = dfs(s, t, INF)) > 0) flow += f;
        }
        return flow;
    }
};

constexpr int dx[4] = {1, 0, -1, 0};
constexpr int dy[4] = {0, 1, 0, -1};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, M, white = 0, black = 0;
    cin >> N >> M;
    vector<vector<int>> S(N, vector<int>(M));
    Dinic<int> d(N * M + 2);
    int s = N * M, t = s + 1;
    for(int i = 0; i < N; ++i){
        for(int j = 0; j < M; ++j){
            char ch;
            cin >> ch;
            if(ch == 'w'){
                white += 1;
                S[i][j] = 1;
            }
            else if(ch == 'b'){
                black += 1;
                S[i][j] = -1;
            }
            if((i + j) % 2 == 0)    d.add_edge(s, M * i + j, 1);
            else    d.add_edge(M * i + j, t, 1);
        }
    }
    for(int x = 0; x < N; ++x){
        for(int y = 0; y < M; ++y){
            if((x + y) % 2 == 1)    continue;
            for(int i = 0; i < 4; ++i){
                int nx = x + dx[i], ny = y + dy[i];
                if(nx < 0 || nx >= N || ny < 0 || ny >= M)  continue;
                if(S[x][y] * S[nx][ny] == -1){
                    d.add_edge(M * x + y, M * nx + ny, 1);
                }
            }
        }
    }
    int match = d.max_flow(s, t);
    cout << match * 100 + (min(white, black) - match) * 10 + max(white, black) - min(white, black) << endl;

    return 0;
}