package No400番台;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;

public class Q421_0 {

	int[] dx = { 1, -1, 0, 0 };
	int[] dy = { 0, 0, 1, -1 };
	int h, w;
	char[][] choco;
	int[][] comp;
	HashMap<Integer, Pair> map = new HashMap<>();

	@SuppressWarnings("unchecked")
	void solver() {
		h = ni();
		w = ni();

		assert 1 <= h && h <= 100 && 1 <= w && w <= 100;

		choco = new char[h][w];
		for (int i = 0; i < h; i++) {
			choco[i] = ns().toCharArray();
			assert choco[i].length == w;
		}

		comp = new int[h][w];
		for (int i = 0; i < h; i++) {
			Arrays.fill(comp[i], -1);
		}

		int color = 0;
		int ans = 0;
		int odd = 0, even = 0;

		ArrayList<Integer>[] g = new ArrayList[h * w];
		for (int i = 0; i < h * w; i++) {
			g[i] = new ArrayList<>();
		}
		for (int y = 0; y < h; y++) {
			for (int x = 0; x < w; x++) {

				assert (x + y) % 2 == 0 ? choco[y][x] != 'b' : choco[y][x] != 'w';

				if (on_filed(x, y) && comp[y][x] == -1) {

					ArrayDeque<Pair> que = new ArrayDeque<>();
					que.add(new Pair(x, y));
					while (!que.isEmpty()) {
						Pair p = que.poll();
						if (comp[p.y][p.x] != -1)
							continue;
						comp[p.y][p.x] = color;

						if ((p.x + p.y) % 2 == 0)
							even++;
						else
							odd++;

						for (int i = 0; i < 4; i++) {
							int nx = p.x + dx[i];
							int ny = p.y + dy[i];
							if (on_filed(nx, ny) && comp[ny][nx] == -1) {

								int a = id(p.x, p.y);
								int b = id(nx, ny);
								map.put(a, new Pair(p.x, p.y));
								map.put(b, new Pair(nx, ny));
								g[a].add(b);
								g[b].add(a);

								que.add(new Pair(nx, ny));
							}
						}
					}
					color++;
				}
			}
		}
		int the_number_of_matchings = bipartiteMatching(g, (h * w + 1) / 2);
		ans += the_number_of_matchings * 100;
		even -= the_number_of_matchings;
		odd -= the_number_of_matchings;

		// show_comp();

		int common = Math.min(even, odd);
		ans += common * 10;
		even -= common;
		odd -= common;
		ans += even + odd;
		out.println(ans);
	}

	int id(int x, int y) {
		if ((y + x) % 2 == 0)
			return (y * w + x) / 2;
		else
			return (y * w + x) / 2 + (h * w - 1) / 2 + 1;
	}

	boolean on_filed(int x, int y) {
		if (0 <= x && x < w && 0 <= y && y < h && choco[y][x] != '.') {
			return true;
		} else
			return false;
	}

	class Pair {
		int x;
		int y;

		Pair(int x, int y) {
			this.x = x;
			this.y = y;
		}
	}

	boolean augment(ArrayList<Integer>[] g, int u, Integer[] matchTo, Boolean[] visited) {
		if (u < 0)
			return true;
		for (int v : g[u]) {
			if (!visited[v]) {
				visited[v] = true;
				if (augment(g, matchTo[v], matchTo, visited)) {
					matchTo[u] = v;
					matchTo[v] = u;
					return true;
				}
			}
		}
		return false;
	}

	int bipartiteMatching(ArrayList<Integer>[] g, int L) {
		final int n = g.length;
		Integer[] matchTo = new Integer[n];
		Arrays.fill(matchTo, -1);
		matching = new ArrayList<>();
		int match = 0;

		for (int i = 0; i < L; i++) {
			Boolean[] visited = new Boolean[n];
			Arrays.fill(visited, false);
			if (augment(g, i, matchTo, visited))
				match++;
		}
		for (int i = 0; i < L; i++) {
			if (matchTo[i] > 0)
				matching.add(new Edge(i, matchTo[i]));
		}

		return match;
	}

	ArrayList<Edge> matching;

	class Edge {
		int a;
		int b;

		Edge(int a, int b) {
			this.a = a;
			this.b = b;
		}
	}

	void show_comp() {
		for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				System.out.print((comp[i][j] == -1 ? "#" : comp[i][j]) + " ");
			}
			System.out.println();
		}
	}

	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";

	public static void main(String[] args) throws Exception {
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);

		new Q421_0().solver();
		out.flush();
	}

	static long nl() {
		try {
			long num = 0;
			boolean minus = false;
			while ((num = is.read()) != -1 && !((num >= '0' && num <= '9') || num == '-'))
				;
			if (num == '-') {
				num = 0;
				minus = true;
			} else {
				num -= '0';
			}

			while (true) {
				int b = is.read();
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
			}
		} catch (IOException e) {
		}
		return -1;
	}

	static char nc() {
		try {
			int b = skip();
			if (b == -1)
				return 0;
			return (char) b;
		} catch (IOException e) {
		}
		return 0;
	}

	static double nd() {
		try {
			return Double.parseDouble(ns());
		} catch (Exception e) {
		}
		return 0;
	}

	static String ns() {
		try {
			int b = skip();
			StringBuilder sb = new StringBuilder();
			if (b == -1)
				return "";
			sb.append((char) b);
			while (true) {
				b = is.read();
				if (b == -1)
					return sb.toString();
				if (b <= ' ')
					return sb.toString();
				sb.append((char) b);
			}
		} catch (IOException e) {
		}
		return "";
	}

	public static char[] ns(int n) {
		char[] buf = new char[n];
		try {
			int b = skip(), p = 0;
			if (b == -1)
				return null;
			buf[p++] = (char) b;
			while (p < n) {
				b = is.read();
				if (b == -1 || b <= ' ')
					break;
				buf[p++] = (char) b;
			}
			return Arrays.copyOf(buf, p);
		} catch (IOException e) {
		}
		return null;
	}

	public static byte[] nse(int n) {
		byte[] buf = new byte[n];
		try {
			int b = skip();
			if (b == -1)
				return null;
			is.read(buf);
			return buf;
		} catch (IOException e) {
		}
		return null;
	}

	static int skip() throws IOException {
		int b;
		while ((b = is.read()) != -1 && !(b >= 33 && b <= 126))
			;
		return b;
	}

	static boolean eof() {
		try {
			is.mark(1000);
			int b = skip();
			is.reset();
			return b == -1;
		} catch (IOException e) {
			return true;
		}
	}

	static int ni() {
		try {
			int num = 0;
			boolean minus = false;
			while ((num = is.read()) != -1 && !((num >= '0' && num <= '9') || num == '-'))
				;
			if (num == '-') {
				num = 0;
				minus = true;
			} else {
				num -= '0';
			}

			while (true) {
				int b = is.read();
				if (b >= '0' && b <= '9') {
					num = num * 10 + (b - '0');
				} else {
					return minus ? -num : num;
				}
			}
		} catch (IOException e) {
		}
		return -1;
	}
}