跳到主要内容
图灵 OJTURING / ONLINE JUDGE

#F0961. Pavel and barbecue

    ID: 967 传统题 2000ms 256MiB 尝试: 0 已通过: 0 难度: 5 上传者: 标签>构造搜索算法思想进阶难度共享题库Codeforces英文题面题目来源题面语言

Pavel and barbecue

题目描述

A. Pavel and barbecue
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

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 b1,b2,...,bn, consisting of zeros and ones. Each second Pavel move skewer on position i to position pi, and if bi 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 2n 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≥2n), so that after k seconds each skewer visits each of the 2n placements.

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

Input

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

The second line contains a sequence of integers p1,p2,...,pn (1≤pin)− the permutation, according to which Pavel wants to move the skewers.

The third line contains a sequence b1,b2,...,bn consisting of zeros and ones, according to which Pavel wants to reverse the skewers.

Output

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 2n placements.

Examples
Input
4
4 3 2 1
0 1 1 1
Output
2
Input
3
2 3 1
0 0 0
Output
1
Note

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.


题目来源:fps-www.educg.net-codeforce-1-2833.xml.zip;FPS 共享题包,题包内第 401 题。保留原作者与原赛事署名。