N,M = map(int,input().split()) 
S = []
def tmp(x):
    if x == 'o':
        return 1
    else:
        return 0
for _ in range(N):
    s = list(map(tmp,list(input())))
    S.append(s)
cnt = [0 for _ in range(M)]
for h in range(N):
    for w in range(M):
        cnt[w] += S[h][w]
ans = 0
for w in range(M):
    k = N-cnt[w] + 1
    ans = max(k,ans)
print(ans)