import sequtils,strutils
var
    N = stdin.readline.parseInt
    hyou = newSeq[string](N)
    cnt : int
    ans = 1000
    
    
proc zyuni(X : openarray[string]):int=
    var x = X[0].count("o")
    var s : set[int8]
    for i,y in X:
        if i == 0:
            continue
        if y.count("o") > x:
            s.incl(y.count("o").int8)
    return s.card + 1
    
    
for n in 0..<N:
    hyou[n] = stdin.readline
    cnt += hyou[n].count("-")
cnt = cnt div 2


for i in 0..<(1 shl cnt):
    var j = i
    var hyou2 = hyou
    for y,h in hyou2:
        for x,w in h:
            if w == '-':
                if j mod 2 == 1:
                    hyou2[y][x] = 'o'
                    hyou2[x][y] = 'x'
                else:
                    hyou2[y][x] = 'x'
                    hyou2[x][y] = 'o'
                j = j shr 1
    ans = min(ans,zyuni(hyou2))
echo ans