n, m = map(int, input().split())
count = [0] * m

for _ in range(n):
    s = input().strip()
    for j in range(m):
        if s[j] == 'o':
            count[j] += 1

max_k = 0
for j in range(m):
    required = n - count[j] + 1
    if required > max_k:
        max_k = required

print(max_k)