#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <tuple>
#include <utility>
#include <vector>
#define ll long long
#define itn int
#define endl '\n'
#define co(ans) cout<<ans<<endl
#define COYE cout<<"YES"<<endl
#define COYe cout<<"Yes"<<endl
#define COye cout<<"yes"<<endl
#define CONO cout<<"NO"<<endl
#define CONo cout<<"No"<<endl
#define COno cout<<"no"<<endl
#define FORE(i,a) for(auto &i:a)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define FFOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n)  FFOR(i,1,n)
#define PB push_back
#define MP make_pair
#define ALL(V) (V).begin(),(V).end()
#define SORT(V) sort((V).begin(),(V).end())
#define REVERSE(V) reverse((V).begin(),(V).end())
#define EACH(V,i) for(typeof((V).begin()) i=(V).begin();i!=(V).end();++i)
#define equals(a,b) (fabs((a)-(b))<EPS)
#define INF ((1LL<<62)-(1LL<<31))
#define EPS 1e-10
#define PI 3.141592653589793238
#define MOD 1000000007
#define MAX 5100000
using namespace std;
using Edge=pair<ll,ll>;
using Graph=vector<vector<int>>;
inline int toInt(string s){int v;istringstream sin(s);sin>>v;return v;}
template<class T>inline string toString(T x){ostringstream sout;sout<<x;return sout.str();}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return 1;}return 0;}
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};
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;}

int main(){
  ll N,K,ans=-INF;
  cin>>N>>K;
  ll P[N],C[N];
  bool SEEN[N],MINUS=false;
  REP(i,N){
    cin>>P[i];
    P[i]--;
    SEEN[i]=false;
  }
  REP(i,N){
    cin>>C[i];
    if(C[i]>0) MINUS=true;
  }
  
  if(MINUS==false){
    ll mn=INF;
    REP(i,N){
      chmin(mn,abs(C[i]));
    }
    co(-mn);
    return 0;
  }
  
  REP(i,N){
    if(SEEN[i]==false){
      queue<ll> Q;
      Q.push(i);
      SEEN[i]=true;
      
      ll roop=0;
      vector<ll> LOOP;
      LOOP.PB(i);
      
      while(!Q.empty()){
        ll v=Q.front();
        Q.pop();
        roop+=C[v];
        SEEN[v]=true;
        if(SEEN[P[v]]==false){
          LOOP.PB(P[v]);
          SEEN[P[v]]=true;
          Q.push(P[v]);
        }
      }
      
      ll cnt=roop*((K-1)/(ll)LOOP.size()),EXP=(K-1)%(ll)LOOP.size()+1;
      if(roop<0){
        cnt=0;
        EXP=min(K,(ll)LOOP.size());
      }
      
      ll size=(ll)LOOP.size();
      REP(i,size){
        LOOP.PB(LOOP[i]);
      }
      
      ll SUM[size*2+10];
      SUM[0]=0;
      REP(i,2*size){
        SUM[i+1]=SUM[i]+C[LOOP[i]];
      }
      
      ll mx=-INF;
      if(roop>=0 && K>=size){
        for(int i=0; i<=size; ++i){
          for(int j=0; j<=EXP; ++j){
            chmax(mx,SUM[i+j]-SUM[i]);
          }
        }
      }
      else{
        for(int i=0; i<=size; ++i){
          for(int j=1; j<=EXP; ++j){
            chmax(mx,SUM[i+j]-SUM[i]);
          }
        }
      }
      
      chmax(ans,cnt+mx);
    }
  }
  
  co(ans);
  return 0;
}

Measured memory_bytes: 3864