from itertools import product
from copy import deepcopy

N=int(input())
S=[]
R=[]
for i in range(N):
    S.append(list(input()))
    for j in range(i+1,N):
        if S[-1][j]=="-":
            R.append((i,j))

rank=N
for t in product([0,1],repeat=len(R)):
    for k,(i,j) in enumerate(R):
        if t[k]==1:
            S[i][j],S[j][i]="o","x"
        else:
            S[i][j],S[j][i]="x","o"

    X=set()
    for i in range(N):
        X.add(S[i].count("o"))
    X=sorted(X,reverse=True)

    rank=min(rank,X.index(S[0].count("o"))+1)

    for i,j in R:
        S[i][j]=S[j][i]="-"

print(rank)