N=int(raw_input())
table=[]
n_null=0
for i in range(N):
    s= raw_input()
    table.append(s)
    for t in s:
        if t=='-':
            n_null+=1
n_null/=2
bestans=N
for mask in range(1<<n_null):
    n_win=[0 for i in range(N)]
    ind=0
    for i in range(N):
        for j in range(i+1,N):
            if table[i][j]=='o':
                n_win[i]+=1
            elif table[i][j]=='x':
                n_win[j]+=1
            else:
                if (mask&(1<<ind))!=0:
                    n_win[i]+=1
                else:
                    n_win[j]+=1
                ind+=1
    ans=1
    for i in range(1,N):
        if n_win[i]>n_win[0]:
            ans+=1
    bestans=min(ans,bestans)
print bestans