N = int(input())
res = [list(input()) for i in range(N)]

def dfs():
    ans = N
    cntmada = 0
    for i in range(N):
        for j in range(i + 1, N):
            if res[i][j] == "-":
                cntmada += 1
                res[i][j] = "o"
                res[j][i] = "x"
                ans = min(ans, dfs())
                res[i][j] = "x"
                res[j][i] = "o"
                ans = min(ans, dfs())
                res[i][j] = "-"
                res[j][i] = "-"
    if cntmada == 0:
        cnt = [0] * N
        for i in range(N):
            for j in range(N):
                if i == j:
                    continue
                if res[i][j] == "o":
                    cnt[i] += 1
        cntsorted = sorted(list(set(cnt)), reverse = True)
        return cntsorted.index(cnt[0]) + 1
    return ans
print(dfs())