n = int(input())
b = [input() for _ in range(n)]
s = ["x" if bi=="x" else "o" for bi in b[0]]
b[0] = "".join(s)
#print(b)

ans = 6
r = [0]*n

def dfs(i,j):
    global ans
    if i==n-1:
        sr = sorted(r,reverse=True)
        ans = min(ans,sr.index(r[0])+1)
        return
    if i >= j: return dfs(i,j+1)
    
        
    ni,nj = i,j+1
    if nj >= n:
        nj = 0
        ni = i+1
    
    if b[i][j] == "o":
        r[i] += 1
        dfs(ni,nj)
    elif b[i][j] == "x":
        r[j] += 1
        dfs(ni,nj)
    else:
        r[i] += 1
        dfs(ni,nj)
        r[i] -= 1
        r[j] += 1
        dfs(ni,nj)
        r[j] -= 1

dfs(0,0)
print(ans)