n, m = map(int, input().split())
board = []
for _ in range(n):
board.append(input())
count = []
for i in range(n-7):
for j in range(m-7):
w_cnt = 0
b_cnt = 0
for r in range(i, i+8):
for c in range(j, j+8):
if (r+c) % 2 == 0:
if board[r][c] != 'W':
w_cnt += 1
if board[r][c] != 'B':
b_cnt += 1
else:
if board[r][c] != 'B':
w_cnt += 1
if board[r][c] != 'W':
b_cnt += 1
count.append(min(w_cnt, b_cnt))
print(min(count))
코드 설명