h, w = map(int, input().split())
A = [input() for _ in range(h)]

f = lambda x, y: x*w+y
g = lambda x: divmod(x, w)


from atcoder.maxflow import MFGraph
n = h*w+2
G = MFGraph(n)
st = n-2
ed = n-1
add = G.add_edge
cnt0 = 0
cnt1 = 0
for i in range(h):
  for j in range(w):
    if A[i][j]=='w':
      add(st, f(i, j), 1)
      cnt0 += 1
    else:
      if A[i][j]=='b':
        add(f(i, j), ed, 1)
        cnt1 += 1
      continue
    for di, dj in (0, 1), (1, 0), (-1, 0), (0, -1):
      ni, nj = i+di, j+dj
      if 0<=ni<h and 0<=nj<w and A[ni][nj]=='b':
        add(f(i, j), f(ni, nj), 1)

t = G.flow(st, ed)
print(100*t + (min(cnt0, cnt1)-t)*10 + abs(cnt0-cnt1))