#!/usr/bin/env PyPy3

from collections import Counter, defaultdict, deque
import itertools
import re
import math
from functools import reduce
import operator
import bisect
import heapq
import functools
mod=10**9+7

import sys
input=sys.stdin.readline

n,m=map(int,input().split())
s=[input().rstrip() for _ in range(n)]
ans = n
for j in range(m):
    c = 0
    for i in range(n):
        if s[i][j] == 'o':
            c += 1
    ans = min(ans,c)
print(n-ans+1)