#!/usr/bin/env python3.8
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
from collections import deque


# %%
class Dinic:
    def __init__(self, N, source, sink):
        self.N = N
        self.G = [[] for _ in range(N)]
        self.source = source
        self.sink = sink

    def add_edge(self, fr, to, cap):
        n1 = len(self.G[fr])
        n2 = len(self.G[to])
        self.G[fr].append([to, cap, n2])
        self.G[to].append([fr, 0, n1])  # 逆辺を cap 0 で追加

    def add_edge_undirected(self, fr, to, cap):
        n1 = len(self.G[fr])
        n2 = len(self.G[to])
        self.G[fr].append([to, cap, n2])
        self.G[to].append([fr, cap, n1])

    def bfs(self):
        level = [0] * self.N
        G = self.G
        source = self.source
        sink = self.sink
        q = deque([source])
        level[source] = 1
        pop = q.popleft
        append = q.append
        while q:
            v = pop()
            lv = level[v] + 1
            for to, cap, rev in G[v]:
                if not cap:
                    continue
                if level[to]:
                    continue
                level[to] = lv
                if to == sink:
                    self.level = level
                    return
                append(to)
        self.level = level

    def dfs(self):
        INF = 10**18
        G = self.G
        sink = self.sink
        prog = self.progress
        level = self.level
        ascend = False
        ff = 0
        stack = [(self.source, INF)]
        while stack:
            if ff:
                # このまま更新だけして戻っていく
                v, f = stack.pop()
                p = prog[v]
                to, cap, rev = G[v][p]
                G[v][p][1] -= ff
                G[to][rev][1] += ff
                continue
            v, f = stack[-1]
            if v == sink:
                ff = f
                stack.pop()
                continue
            E = G[v]
            lv = level[v]
            if ascend:
                # 流せずに戻ってきた
                prog[v] += 1
            find_flag = False
            for i in range(prog[v], len(E)):
                to, cap, rev = E[i]
                prog[v] = i
                if not cap:
                    continue
                if level[to] <= lv:
                    continue
                find_flag = True
                break
            if not find_flag:
                ascend = True
                stack.pop()
                continue
            ascend = False
            x = f if f < cap else cap
            stack.append((to, x))
        return ff

    def max_flow(self):
        flow = 0
        while True:
            self.bfs()
            if not self.level[self.sink]:
                return flow
            self.progress = [0] * self.N
            while True:
                f = self.dfs()
                if not f:
                    break
                flow += f
        return flow


# %%
H, W = map(int, readline().split())
S = list(''.join(read().decode().split()))


# %%
source = H * W
sink = H * W + 1
dinic = Dinic(N=H * W + 2, source=source, sink=sink)
for h in range(H - 1):
    for w in range(W):
        i = W * h + w
        j = i + W
        if S[i] == 'b' and S[j] == 'w':
            dinic.add_edge(i, j, 1)
        elif S[i] == 'w' and S[j] == 'b':
            dinic.add_edge(j, i, 1)
for h in range(H):
    for w in range(W - 1):
        i = W * h + w
        j = i + 1
        if S[i] == 'b' and S[j] == 'w':
            dinic.add_edge(i, j, 1)
        elif S[i] == 'w' and S[j] == 'b':
            dinic.add_edge(j, i, 1)
for i in range(H * W):
    if S[i] == 'b':
        dinic.add_edge(source, i, 1)
    elif S[i] == 'w':
        dinic.add_edge(i, sink, 1)


# %%
f = dinic.max_flow()

# %%
B = S.count('b')
W = S.count('w')
score = 100 * f
B -= f
W -= f
x = min(B, W)
score += 10 * x
B -= x
W -= x
score += B + W
print(score)