#include <algorithm>
#include <bitset>
#include <cassert>
#include <complex>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <typeinfo>
#include <utility>
#include <vector>
#include <array>
#include <chrono>
#include <random>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, ...)type __VA_ARGS__;Scan(__VA_ARGS__);
template<typename T> void Scan(T& t) { std::cin >> t; }
template<typename First, typename...Rest>void Scan(First& first, Rest&...rest) { std::cin >> first; Scan(rest...); }
#define OUT(d) std::cout<<d;
#define FOUT(n, d) std::cout<<std::fixed<<std::setprecision(n)<<d;
#define SOUT(n, c, d) std::cout<<std::setw(n)<<std::setfill(c)<<d;
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define FLUSH std::cout<<std::flush;
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n) for(int i=0;i<int(n);++i)
#define RREP(i, n) for(int i=(n)-1;i>=0;--i)
#define FORLL(i, a, b) for(ll i=ll(a);i<ll(b);++i)
#define RFORLL(i, a, b) for(ll i=ll(b)-1;i>=ll(a);--i)
#define REPLL(i, n) for(ll i=0;i<ll(n);++i)
#define RREPLL(i, n) for(ll i=ll(n)-1;i>=0;--i)
#define PAIR std::pair<int, int>
#define IN(a, x, b) (a<=x && x<b)
#define SHOW(d) {std::cout << #d << "\t:" << d << "\t";}
#define SHOWVECTOR(v) {std::cout << #v << "\t:";for(const auto& i : v){std::cout << i << " ";}std::cout << "\n";}
#define SHOWVECTOR2(v) {std::cout << #v << "\t:\n";for(const auto& i : v){for(const auto& j : i){std::cout << j << " ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR2(v) {std::cout << #v << "\t:\n";for(const auto& i : v){for(const auto& j : i){std::cout<<'('<<j.first<<", "<<j.second<<") ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR(v) {for(const auto& i:v){std::cout<<'('<<i.first<<", "<<i.second<<") ";}std::cout<<"\n";}
#define CHECKTIME(state) {auto start=std::chrono::system_clock::now();state();auto end=std::chrono::system_clock::now();auto res=std::chrono::duration_cast<std::chrono::nanoseconds>(end-start).count();std::cerr<<"[Time:"<<res<<"ns  ("<<res/(1.0e9)<<"s)]\n";}
#define SHOWQUEUE(a) {std::queue<decltype(a.front())> tmp(a);std::cout << #a << "\t:";for(int i=0; i<static_cast<int>(a.size()); ++i){std::cout << tmp.front() << "\n";tmp.pop();}std::cout << "\n";}

//#define int ll
using ll = long long;
using ull = unsigned long long;
constexpr int INFINT = 1 << 30;
constexpr ll INFLL = 1LL << 60;
constexpr double EPS = 0.0000000001;
constexpr int MOD = 1000000007;

class Dinic {
private:
	struct Edge {
		int to, cap, rev;
		Edge(int t, int c, int r) :to(t), cap(c), rev(r){}
	};
	int V;
	std::vector<std::vector<Edge>> graph;
	std::vector<int> level, iter;

public:
	Dinic(int v) : V(v) {
		graph.resize(v);
		level.resize(v, -1);
		iter.resize(v, 0);
	}
	// fromからtoへ向かう容量capの辺をグラフに追加する
	void addEdge(int from, int to, int cap) {
		graph[from].emplace_back(to, cap, graph[to].size());
		graph[to].emplace_back(from, 0, graph[from].size() - 1);
	}

	// sからの最短距離をBFSで計算する
	void bfs(int s) {
		std::fill(level.begin(), level.end(), -1);
		std::queue<int> queue;
		level[s] = 0;
		queue.push(s);
		while (!queue.empty()) {
			int v = queue.front(); queue.pop();
			for (int i = 0; i < graph[v].size(); ++i) {
				Edge& e = graph[v][i];
				if (e.cap > 0 && level[e.to] < 0) {
					level[e.to] = level[v] + 1;
					queue.push(e.to);
				}
			}
		}
	}

	// 増加パスをDFSで探す
	int dfs(int v, int t, int f) {
		if (v == t) return f;
		for (int& i = iter[v]; i < graph[v].size(); ++i) {
			Edge& e = graph[v][i];
			if (e.cap > 0 && level[v] < level[e.to]) {
				int d = dfs(e.to, t, std::min(f, e.cap));
				if (d > 0) {
					e.cap -= d;
					graph[e.to][e.rev].cap += d;
					return d;
				}
			}
		}
		return 0;
	}

	// sからtへの最大流を求める
	int maxFlow(int s, int t) {
		int res = 0;
		while (true) {
			bfs(s);
			if (level[t] < 0) return res;
			std::fill(iter.begin(), iter.end(), 0);
			int f;
			while ((f = dfs(s, t, (1LL << 31) - 1)) > 0) {
				res += f;
			}
		}
	}
};

signed main() {
	INIT;
	VAR(int, n, m);
	MAT(char, a, n, m);
	int s = n*m, t = n*m + 1;
	Dinic g(n*m + 2);
	int w = 0, b = 0;
	auto pos = [&](int i, int j) {return i*m + j; };
	REP(i, n) REP(j, m) {
		switch (a[i][j]) {
		case 'w': {
			g.addEdge(s, pos(i, j), 1);
			++w;
			if (i != 0 && a[i - 1][j] == 'b') g.addEdge(pos(i, j), pos(i - 1, j), 1);
			if (j != 0 && a[i][j - 1] == 'b') g.addEdge(pos(i, j), pos(i, j - 1), 1);
			if (i != n - 1 && a[i + 1][j] == 'b') g.addEdge(pos(i, j), pos(i + 1, j), 1);
			if (j != m - 1 && a[i][j + 1] == 'b') g.addEdge(pos(i, j), pos(i, j + 1), 1);
			break;
		}
		case 'b': {
			g.addEdge(pos(i, j), t, 1);
			++b;
			break;
		}
		}
	}
	int maxFlow = g.maxFlow(s, t);
	int ans = 100 * maxFlow;
	w -= maxFlow;
	b -= maxFlow;
	ans += 10 * std::min(w, b);
	ans += std::max(w, b) - std::min(w, b);
	OUT(ans)BR;
	return 0;
}