python3
N, M = map(int, input().split())
wall = []
for i in range(N):
wall.append(input())
T = [-1 for _ in range(M)]
count = 0
if wall[N-1][0] == ‘B’:
count = 1
for i in range(1, M):
if wall[N-1][i-1] == ‘.’ and wall[N-1][i] == ‘B’:
count += 1
print(count)