import itertools
N = int(input())
S = [list(input()) for _ in range(N)]

count = 0
for s in S:
    for m in s:
        if m == '-':
            count += 1
    
rg = count//2
WL = ('o','x')
pat = []
for p in itertools.product(WL, repeat=rg):
    pat.append(list(p))

CS = [x[:] for x in S]
rup = []
for g in pat:
    wn = []
    for idx, ss in enumerate(S):
        for idxx, sss in enumerate(ss):
            if CS[idx][idxx] == '-':
                wl = g.pop()
                if wl == 'o':
                    CS[idx][idxx] = 'o'
                    CS[idxx][idx] = 'x'
                else:
                    CS[idx][idxx] = 'x'
                    CS[idxx][idx] = 'o'
    for cs in CS:
        w = cs.count('o')
        wn.append(w)
    tw = wn[0]
    swn = list(set(wn))
    wn = sorted(swn, reverse=True)
    rank = wn.index(tw) + 1
    rup.append(rank)
    CS = [x[:] for x in S]

print(min(rup))