N = int(input())
S = []
cnt = 0
D = []
for i in range(N):
    S.append(list(input()))
    for j in range(N):
        if S[i][j] == "-" and i < j:
            D.append((i, j))
            cnt += 1
    
if cnt == 0:
    L = []
    for i in range(N):
        L.append(S[i].count("o"))
    SL = sorted(list(set(L)))
    print(len(SL) - SL.index(L[0]))
    exit()
    
ans = 10 ** 18
for i in range(1 << cnt):
    A = [[0] * N for i in range(N)]
    for a in range(N):
        for b in range(N):
            A[a][b] = S[a][b]
    for j in range(cnt):
        x, y = D[j]
        if (i >> j) & 1:
            A[x][y] = "o"
            A[y][x] = "x"
        else:
            A[x][y] = "x"
            A[y][x] = "o"
    L = []
    for i in range(N):
        L.append(A[i].count("o"))
    SL = sorted(list(set(L)))
    ans = min(ans, len(SL) - SL.index(L[0]))
print(ans)