#yuki43
from itertools import product

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))
res=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)

 res=min(res,x.index(s[0].count('o'))+1)

 for i,j in r:
  s[i][j]=s[j][i]='-'

print(res)