#define LOCAL
#define _USE_MATH_DEFINES
#include <array>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <complex>
#include <cmath>
#include <numeric>
#include <bitset>
#include <functional>
#include <random>
#include <ctime>

using namespace std;

template <typename A, typename B>
ostream& operator <<(ostream& out, const pair<A, B>& a) {
  out << "(" << a.first << "," << a.second << ")";
  return out;
}
template <typename T, size_t N>
ostream& operator <<(ostream& out, const array<T, N>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const vector<T>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T, class Cmp>
ostream& operator <<(ostream& out, const set<T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "}";
  return out;
}
template <typename U, typename T, class Cmp>
ostream& operator <<(ostream& out, const map<U, T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& p : a) { out << (first ? "" : ", "); out << p.first << ":" << p.second; first = 0;} out << "}";
  return out;
}
#ifdef LOCAL
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
#else
#define trace(...) 42
#endif
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}

typedef long long int64;
typedef pair<int, int> ii;
#define SZ(x) (int)((x).size())
const int INF = 1 << 29;
const int MOD = 1e9 + 7;
mt19937 mrand(random_device{}());
int rnd(int x) { return mrand() % x; }

struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
  };
} fast_ios_;

int main() {
  int n, m;
  cin >> n >> m;
  vector<int> p(n), c(n);
  for (int i = 0; i < n; ++i) cin >> p[i], --p[i];
  for (int i = 0; i < n; ++i) cin >> c[i];

  vector<int64> sum(n), len(n);
  for (int i = 0; i < n; ++i) {
    sum[i] = c[i];
    len[i] = 1;
    for (int j = p[i]; j != i; j = p[j]) sum[i] += c[j], len[i]++;
  }

  int64 best = -(1LL << 60);
  for (int i = 0; i < n; ++i) {
    int64 cur = 0;
    if (sum[i] > 0 && m / len[i] > 1) {
      int64 q = m / len[i];
      cur += (q - 1) * sum[i];
      int r = m % len[i] + len[i];
      int64 opt = -(1LL << 60);
      int64 acc = 0;
      for (int j = i, k = 0; k < r; ++k, j = p[j]) {
        acc += c[j];
        opt = max(opt, acc);
      }
      cur += opt;
    } else {
      int64 opt = -(1LL << 60);
      int64 acc = 0;
      for (int j = i, k = 0; k < len[i] * 2 && k < m; ++k, j = p[j]) {
        acc += c[j];
        opt = max(opt, acc);
      }
      cur += opt;
    }
    best = max(best, cur);
  }
  cout << best << endl;
  return 0;
}


Measured memory_bytes: 3316