#include <iostream>
#include <cstdio>
#include <algorithm>
#include <bits/stdc++.h>
#define ALL(x) (x).begin(), (x).end()
#define sz(a) int(a.size())
#define rep(i,x,n) for(int i=x;i<n;i++)
#define repd(i,x,n) for(int i=x;i<=n;i++)
#define pii pair<int,int>
#define pll pair<long long ,long long>
#define gbtb ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define MS0(X) memset((X), 0, sizeof((X)))
#define MSC0(X) memset((X), '\0', sizeof((X)))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define eps 1e-6
#define chu(x)  if(DEBUG_Switch) cout<<"["<<#x<<" "<<(x)<<"]"<<endl
#define du3(a,b,c) scanf("%d %d %d",&(a),&(b),&(c))
#define du2(a,b) scanf("%d %d",&(a),&(b))
#define du1(a) scanf("%d",&(a));
using namespace std;
typedef long long ll;
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a / gcd(a, b) * b;}
ll powmod(ll a, ll b, ll MOD) { if (a == 0ll) {return 0ll;} a %= MOD; ll ans = 1; while (b) {if (b & 1) {ans = ans * a % MOD;} a = a * a % MOD; b >>= 1;} return ans;}
ll poww(ll a, ll b) { if (a == 0ll) {return 0ll;} ll ans = 1; while (b) {if (b & 1) {ans = ans * a ;} a = a * a ; b >>= 1;} return ans;}
void Pv(const vector<int> &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%d", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
void Pvl(const vector<ll> &V) {int Len = sz(V); for (int i = 0; i < Len; ++i) {printf("%lld", V[i] ); if (i != Len - 1) {printf(" ");} else {printf("\n");}}}
inline long long readll() {long long tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') fh = -1; c = getchar();} while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar(); return tmp * fh;}
inline int readint() {int tmp = 0, fh = 1; char c = getchar(); while (c < '0' || c > '9') {if (c == '-') fh = -1; c = getchar();} while (c >= '0' && c <= '9') tmp = tmp * 10 + c - 48, c = getchar(); return tmp * fh;}
void pvarr_int(int *arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%d%c", arr[i], i == n ? '\n' : ' ');}}
void pvarr_LL(ll *arr, int n, int strat = 1) {if (strat == 0) {n--;} repd(i, strat, n) {printf("%lld%c", arr[i], i == n ? '\n' : ' ');}}
const int maxn = 10010;
const int inf = 0x3f3f3f3f;
/*** TEMPLATE CODE * * STARTS HERE ***/
#define DEBUG_Switch 0
int n, k;
int p[maxn];
ll c[maxn];
bool vis[maxn];
int tot;
std::vector<ll> v[maxn];
void dfs(int x)
{
    v[tot].push_back(c[x]);
    if (!vis[p[x]])
    {
        vis[p[x]] = 1;
        dfs(p[x]);
    }
}
std::vector<ll> temp;
ll solve(int id)
{
    ll sum = 0ll;
    for (auto x : v[id])
    {
        sum += x;
    }
    int m = k;
    ll res = 0ll;
    if (sum > 0)
    {
        res += sum * max(k / (sz(v[id])) - 1, 0);
        m = min(k % sz(v[id]) + sz(v[id]), m);
    }
    temp.clear();
    int len = sz(v[id]);
    temp.insert(temp.end(), ALL(v[id]));
    temp.insert(temp.end(), ALL(v[id]));
    ll now = 0ll;
    ll add = -1e18;
    for (int i = 0; i < len; ++i)
    {
        now = 0ll;
        for (int j = 0; j < min(m, len); ++j)
        {
            now = max(temp[i + j], now + temp[i + j]);
            add = max(add, now + max(0ll, 1ll * (m - j - 1) / len * sum ));
        }
    }
    return res + add;
}
int main()
{
#if DEBUG_Switch
    freopen("C:\\code\\input.txt", "r", stdin);
#endif
    //freopen("C:\\code\\output.txt","w",stdout);
    n = readint(); k = readint();
    repd(i, 1, n)
    {
        p[i] = readint();
    }
    repd(i, 1, n)
    {
        c[i] = readll();
    }
    repd(i, 1, n)
    {
        if (!vis[i])
        {
            vis[i] = 1;
            tot++;
            dfs(i);
        }
    }
    ll ans = -1e18;
    repd(i, 1, tot)
    {
        ans = max(ans, solve(i));
    }
    printf("%lld\n", ans );
    return 0;
}




Measured memory_bytes: 4160