import strutils, sequtils, math, sets

var
    fumei = 0
    n = stdin.readLine.parseInt
    strs = newSeq[string](n)

for i in 0.. <n:
    strs[i] = stdin.readLine

for i in 0.. <n:
    for j in i+1.. <n:
        if strs[i][j] == '-':
            fumei += 1

var lag = 19970121 # for lágmark＞(ΦωΦ)
#for m in 0.. <(1 shl fumei): # (ΦωΦ)＜書けない！
#for m in 0.. <1 shl fumei: # (ΦωΦ)＜意味が違うみたい！
#for m in 0..1 shl fumei-1: # (ΦωΦ)＜こっちと下は
for m in 0..(1 shl fumei)-1:# (ΦωΦ)＜どっちでもいいよ！
    var score = newSeq[int](n)
    for i in 0.. <n:
        for j in 0.. <n:
            if strs[i][j] == 'o':
                score[i] += 1
    var p = 0
    for i in 0.. <n:
        for j in i+1.. <n:
            if strs[i][j] == '-':
                if (((m shr p) and 1) == 1):
                    score[i] += 1
                else:
                    score[j] += 1
                p += 1
    var upper = initSet[int]()
    for i in 1.. <n:
        if score[0] < score[i]:
            upper.incl(score[i])
    lag = min(lag, upper.len+1)

echo lag