# Dinic's algorithm
from collections import deque


class Dinic:
    def __init__(self, N):
        self.N = N
        self.G = [[] for i in range(N)]

    def add_edge(self, fr, to, cap):
        forward = [to, cap, None]
        forward[2] = backward = [fr, 0, forward]
        self.G[fr].append(forward)
        self.G[to].append(backward)

    def add_multi_edge(self, v1, v2, cap1, cap2):
        edge1 = [v2, cap1, None]
        edge1[2] = edge2 = [v1, cap2, edge1]
        self.G[v1].append(edge1)
        self.G[v2].append(edge2)

    def bfs(self, s, t):
        self.level = level = [None] * self.N
        deq = deque([s])
        level[s] = 0
        G = self.G
        while deq:
            v = deq.popleft()
            lv = level[v] + 1
            for w, cap, _ in G[v]:
                if cap and level[w] is None:
                    level[w] = lv
                    deq.append(w)
        return level[t] is not None

    def dfs(self, v, t, f):
        if v == t:
            return f
        level = self.level
        for e in self.it[v]:
            w, cap, rev = e
            if cap and level[v] < level[w]:
                d = self.dfs(w, t, min(f, cap))
                if d:
                    e[1] -= d
                    rev[1] += d
                    return d
        return 0

    def flow(self, s, t):
        flow = 0
        INF = 10 ** 9 + 7
        G = self.G
        while self.bfs(s, t):
            *self.it, = map(iter, self.G)
            f = INF
            while f:
                f = self.dfs(s, t, INF)
                flow += f
        return flow


dic = {"w": 0, "b": 1}
N, M = map(int, input().split())
S = [input() for _ in range(N)]
NM = N * M
E = []
# w:NM, b:NM+1
dinic = Dinic(NM + 2)
WB = [0, 0]
edges = []
for i in range(N):
    for j in range(M):
        s = S[i][j]
        if s == ".":
            continue
        c = dic[s]
        ij = i * M + j
        WB[c] += 1
        if c == 0:
            dinic.add_edge(NM, ij, 1)
        else:
            dinic.add_edge(ij, NM + 1, 1)
        if i < N - 1 and S[i + 1][j] != ".":
            ij2 = (i + 1) * M + j
            if c == 0:
                dinic.add_edge(ij, ij2, 1)
            else:
                dinic.add_edge(ij2, ij, 1)
        if j < M - 1 and S[i][j + 1] != ".":
            ij2 = i * M + j + 1
            if c == 0:
                dinic.add_edge(ij, ij2, 1)
            else:
                dinic.add_edge(ij2, ij, 1)
m = dinic.flow(NM, NM + 1)
ans = abs(WB[0] - WB[1])
ans += 100 * m
ans += 10 * (min(WB) - m)
print(ans)