def bfs(i, j):

cnt = 0

adj = []

lookup[i][j] = True

q = [(i, j)]

while q:

new_q = []

for i, j in q:

cnt += 1

for di, dj in DIRECTIONS:

ni, nj = i+di, j+dj

if not (0 <= ni < R and 0 <= nj < C and not lookup[ni][nj]):

continue

lookup[ni][nj] = True

if A[ni][nj] == '.':

adj.append((ni, nj))

continue

new_q.append((ni, nj))

q = new_q

for i, j in adj:

lookup[i][j] = False

return adj, cnt

R, C = list(map(int, input().split()))

A = [list(input()) for _ in range(R)]

result = 0

dp = [[0]*C for _ in range(R)]

lookup = [[A[i][j] == 'B' for j in range(C)] for i in range(R)]

for i in range(R):

for j in range(C):

if not (A[i][j] == 'W' and not lookup[i][j]):

continue

adj, cnt = bfs(i, j)

if len(adj) != 1:

continue

i, j = adj[0]

dp[i][j] += cnt

result = max(result, dp[i][j])