CF756A.Pavel and barbecue

Pavel cooks barbecue. There are n skewers, they lay on a brazier in a row, each on one of n positions. Pavel wants each skewer to be cooked some time in every of n positions in two directions: in the one it was directed originally and in the reversed direction.

Pavel has a plan: a permutation p and a sequence _b_1, _b_2, ..., b__n, consisting of zeros and ones. Each second Pavel move skewer on position i to position p__i, and if b__i equals 1 then he reverses it. So he hope that every skewer will visit every position in both directions.

Unfortunately, not every pair of permutation p and sequence b suits Pavel. What is the minimum total number of elements in the given permutation p and the given sequence b he needs to change so that every skewer will visit each of 2_n_ placements? Note that after changing the permutation should remain a permutation as well.

There is no problem for Pavel, if some skewer visits some of the placements several times before he ends to cook. In other words, a permutation p and a sequence b suit him if there is an integer k (k ≥ 2_n_), so that after k seconds each skewer visits each of the 2_n_ placements.

It can be shown that some suitable pair of permutation p and sequence b exists for any n.

帕维尔正在烤肉。一共有 $n$ 个烤串，它们排成一行，放置在烤架上的 $n$ 个位置上。帕维尔希望每个烤串都能在全部 $n$ 个位置上、且在两个方向（即其原始朝向和翻转后的朝向）各被烤制一段时间。

帕维尔有一个计划：一个排列 $p$ 和一个由 $0$ 和 $1$ 组成的序列 $b_1, b_2, \dots, b_n$。每一秒，帕维尔将位于位置 $i$ 的烤串移动到位置 $p_i$；若 $b_i = 1$，则同时将其翻转。因此，他期望每个烤串最终都能访问全部 $2n$ 种“摆放状态”（即 $n$ 个位置 $\times$ 两种方向）。

遗憾的是，并非任意给定的排列 $p$ 和序列 $b$ 都能满足帕维尔的要求。那么，为使每个烤串最终都能访问全部 $2n$ 种摆放状态，帕维尔至少需要修改排列 $p$ 和序列 $b$ 中多少个元素？注意：修改后，$p$ 仍须是一个合法排列。

只要某个烤串在完成全部烤制前多次访问某些摆放状态，对帕维尔而言并无问题。换言之，排列 $p$ 和序列 $b$ 满足要求，当且仅当存在某个整数 $k$（$k \geq 2n$），使得经过 $k$ 秒后，每个烤串都曾访问过全部 $2n$ 种摆放状态。

可以证明：对任意正整数 $n$，总存在满足要求的排列 $p$ 和序列 $b$。

The first line contain the integer n (1 ≤ n ≤ 2·105) — the number of skewers.

The second line contains a sequence of integers _p_1, _p_2, ..., p__n (1 ≤ p__i ≤ n) — the permutation, according to which Pavel wants to move the skewers.

The third line contains a sequence _b_1, _b_2, ..., b__n consisting of zeros and ones, according to which Pavel wants to reverse the skewers.

第一行包含整数 $n$（$1 ≤ n ≤ 2·10^5$）—— 烤肉签的数量。

第二行包含一个整数序列 $p_1, p_2, ..., p_n$（$1 ≤ p_i ≤ n$）—— Pavel 希望按照该排列移动烤肉签。

第三行包含一个由 0 和 1 组成的序列 $b_1, b_2, ..., b_n$，Pavel 将依据该序列决定是否翻转对应的烤肉签。

Print single integer — the minimum total number of elements in the given permutation p and the given sequence b he needs to change so that every skewer will visit each of 2_n_ placements.

输出一个整数——为使每个烤肉签访问全部 $2n$ 个位置，所需修改给定排列 $p$ 和给定序列 $b$ 中元素的最少总个数。

In the first example Pavel can change the permutation to 4, 3, 1, 2.

In the second example Pavel can change any element of b to 1.

在第一个例子中，帕维尔可以将排列更改为 $4,\ 3,\ 1,\ 2$。

在第二个例子中，帕维尔可以将 $b$ 的任意一个元素更改为 $1$。