mod = 998244353


def main():
    import sys
    input = sys.stdin.readline

    N, M = map(int, input().split())
    S = []
    for _ in range(N):
        S.append(input().rstrip('\n'))

    cnt = [0] * M
    for i in range(N):
        for j in range(M):
            if S[i][j] == "o":
                cnt[j] += 1
    print(N - min(cnt) + 1)


if __name__ == '__main__':
    main()