#![allow(non_snake_case)]
#![allow(dead_code)]
#![allow(unused_macros)]
#![allow(unused_imports)]

use std::str::FromStr;
use std::io::*;
use std::collections::*;
use std::cmp::*;

struct Scanner<I: Iterator<Item = char>> {
    iter: std::iter::Peekable<I>,
}

macro_rules! exit {
    () => {{
        exit!(0)
    }};
    ($code:expr) => {{
        if cfg!(local) {
            writeln!(std::io::stderr(), "===== Terminated =====")
                .expect("failed printing to stderr");
        }
        std::process::exit($code);
    }}
}

impl<I: Iterator<Item = char>> Scanner<I> {
    pub fn new(iter: I) -> Scanner<I> {
        Scanner {
            iter: iter.peekable(),
        }
    }

    pub fn safe_get_token(&mut self) -> Option<String> {
        let token = self.iter
            .by_ref()
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<String>();
        if token.is_empty() {
            None
        } else {
            Some(token)
        }
    }

    pub fn token(&mut self) -> String {
        self.safe_get_token().unwrap_or_else(|| exit!())
    }

    pub fn get<T: FromStr>(&mut self) -> T {
        self.token().parse::<T>().unwrap_or_else(|_| exit!())
    }

    pub fn vec<T: FromStr>(&mut self, len: usize) -> Vec<T> {
        (0..len).map(|_| self.get()).collect()
    }

    pub fn mat<T: FromStr>(&mut self, row: usize, col: usize) -> Vec<Vec<T>> {
        (0..row).map(|_| self.vec(col)).collect()
    }

    pub fn char(&mut self) -> char {
        self.iter.next().unwrap_or_else(|| exit!())
    }

    pub fn chars(&mut self) -> Vec<char> {
        self.get::<String>().chars().collect()
    }

    pub fn mat_chars(&mut self, row: usize) -> Vec<Vec<char>> {
        (0..row).map(|_| self.chars()).collect()
    }

    pub fn line(&mut self) -> String {
        if self.peek().is_some() {
            self.iter
                .by_ref()
                .take_while(|&c| !(c == '\n' || c == '\r'))
                .collect::<String>()
        } else {
            exit!();
        }
    }

    pub fn peek(&mut self) -> Option<&char> {
        self.iter.peek()
    }
}

const INF: i64 = 1 << 60;

fn main() {
    let cin = stdin();
    let cin = cin.lock();
    let mut sc = Scanner::new(cin.bytes().map(|c| c.unwrap() as char));
    let N: usize = sc.get();
    let K: i64 = sc.get();
    let P: Vec<usize> = sc.vec::<usize>(N).into_iter().map(|i| i - 1).collect::<Vec<usize>>();
    let C: Vec<i64> = sc.vec(N);
    let mut ans = -INF;
    for mut s in 0..N {
        let mut seen = HashSet::new();
        seen.insert(s);
        let mut loop_score = 0;
        let mut loop_cnt = 0;
        let mut mx = vec![-INF; N+1];
        let mut mxmx = -INF;
        let mut i = 1;
        loop {
            s = P[s];
            loop_score += C[s];
            loop_cnt += 1;
            mx[i] = max(mx[i-1], loop_score);
            mxmx = max(mxmx, mx[i]);
            if seen.contains(&s) {
                break;
            }
            seen.insert(s);
            i += 1;
        }
        if loop_score <= 0 {
            ans = max(ans, mxmx);
        } else {
            if K/loop_cnt > 0 {
                ans = max(ans, K/loop_cnt*loop_score + max(0, mx[(K % loop_cnt) as usize]));
            } else {
                ans = max(ans, K/loop_cnt*loop_score + mx[(K % loop_cnt) as usize]);
            }
            ans = max(ans, (K/loop_cnt-1)*loop_score + mxmx);
        }
    }
    println!("{}", ans);
}


Measured memory_bytes: 2444