Problem:
Score : 400 points

Problem Statement

Takahashi will play a game using a piece on an array of squares numbered 1, 2, \cdots, N. Square i has an integer C_i written on it. Also, he is given a permutation of 1, 2, \cdots, N: P_1, P_2, \cdots, P_N.

Now, he will choose one square and place the piece on that square. Then, he will make the following move some number of times between 1 and K (inclusive):

In one move, if the piece is now on Square i (1 \leq i \leq N), move it to Square P_i. Here, his score increases by C_{P_i}.

Help him by finding the maximum possible score at the end of the game. (The score is 0 at the beginning of the game.)

Constraints

2 \leq N \leq 5000

1 \leq K \leq 10^9

1 \leq P_i \leq N

P_i \neq i

P_1, P_2, \cdots, P_N are all different.

-10^9 \leq C_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K
P_1 P_2 \cdots P_N
C_1 C_2 \cdots C_N

Output

Print the maximum possible score at the end of the game.

Sample Input 1

5 2
2 4 5 1 3
3 4 -10 -8 8

Sample Output 1

8

When we start at some square of our choice and make at most two moves, we have the following options:

If we start at Square 1, making one move sends the piece to Square 2, after which the score is 4. Making another move sends the piece to Square 4, after which the score is 4 + (-8) = -4.

If we start at Square 2, making one move sends the piece to Square 4, after which the score is -8. Making another move sends the piece to Square 1, after which the score is -8 + 3 = -5.

If we start at Square 3, making one move sends the piece to Square 5, after which the score is 8. Making another move sends the piece to Square 3, after which the score is 8 + (-10) = -2.

If we start at Square 4, making one move sends the piece to Square 1, after which the score is 3. Making another move sends the piece to Square 2, after which the score is 3 + 4 = 7.

If we start at Square 5, making one move sends the piece to Square 3, after which the score is -10. Making another move sends the piece to Square 5, after which the score is -10 + 8 = -2.

The maximum score achieved is 8.

Sample Input 2

2 3
2 1
10 -7

Sample Output 2

13

Sample Input 3

3 3
3 1 2
-1000 -2000 -3000

Sample Output 3

-1000

We have to make at least one move.

Sample Input 4

10 58
9 1 6 7 8 4 3 2 10 5
695279662 988782657 -119067776 382975538 -151885171 -177220596 -169777795 37619092 389386780 980092719

Sample Output 4

29507023469

The absolute value of the answer may be enormous.

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

    #include<bits/stdc++.h>
    // #include<ext/pb_ds/assoc_container.hpp>
    // #include<ext/pb_ds/tree_policy.hpp>
using namespace std;
        // using namespace __gnu_pbds;

typedef long long int lli;
typedef unsigned long long int ull;
typedef long double ld;
typedef pair<lli,lli> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii>vpii;
typedef std::vector<lli> vll;
typedef std::vector<pll> vpll;
typedef std::vector<bool> vbb;
typedef map<lli,lli>mll;
typedef set<lli> sll;
typedef multiset<lli> msll;
lli MOD=1e9 +7;
lli INF=1e18;

    #define forr(i,p,n) for(i=p; i<n; i++)
    #define forn(i,p,n) for(i=p; i<=n; i++)
    #define forl(i,n,p) for(i=n; i>=p; i--)
    #define be(a) a.begin(),a.end()
    #define mp make_pair            
    #define eb emplace_back 
    #define pb push_back 
    #define F first
    #define S second
    #define all(a)     (a).begin(),(a).end()
    #define PI 3.14159265358979323846
    #define lb lower_bound
    #define ub upper_bound
    #define endl "\n"
    #define bpcl(x) __builtin_popcountll(x)
    #define deb(vari) cerr<<#vari<<" = "<<vari<<endl;
                // #define ordered_set tree<lli, null_type,less<lli>, rb_tree_tag,tree_order_statistics_node_update> 
lli power(lli base, lli exp) {lli res=1;while(exp>0) {if(exp%2==1) res=(res*base);base=(base*base);exp/=2;}return res;}
lli bitc(lli n,lli x){return ((n>>x)&1);}
lli __gcd(lli a,lli b){return b==0?a:__gcd(b,a%b);}
lli fsub(lli a,lli b,lli p=MOD){return ((a%p)-(b%p)+p)%p;}
lli fmult(lli a,lli b, lli p=MOD) {return ((a%p)*(b%p))%p;}
lli fadd(lli a, lli b, lli p=MOD) {return (a%p + b%p)%p;}
                                        // lli add(lli a,lli b,lli p=MOD){//if(a+b>=p){//return (a+b)-p;//  }//return a+b;// }
lli fpow(lli n, lli k, lli p = MOD) {lli r = 1; while(k > 0) {if (k & 1) r = r * n%p; n = n * n%p; k = k >> 1;} return r;}
lli inv(lli a, lli p = MOD) {return fpow(a, p - 2, p);}
lli fdiv(lli a,lli b,lli p=MOD){lli yinv=inv(b);lli ans=(a*yinv)%p;return ans;}

    template<typename T>istream &operator>>(istream &in, vector<T> &a) {for (auto &item : a) {in >> item;}return in;}template<typename T,typename U>ostream &operator<<(ostream &out, pair<T,U> &a) {cout<<a.F<<" "<<a.S;return out;}
    template<typename T,typename U>
istream &operator>>(istream &out, pair<T,U> &a) {cin>>a.F>>a.S;return out;}
    template<typename T,typename U>
ostream &operator<<(ostream &out, map<T,U> &a) {for (auto &item : a) {out << item << endl;}return out;}
    template<typename T>
ostream &operator<<(ostream &out, vector<T> &a) {for (auto &item : a) {out << item << " ";}return out;}
    template<typename T>
ostream &operator<<(ostream &out, vector<vector<T>> &a) {for (auto &item : a) {out << item << "\n";}return out;}
    template<int D, typename T>
struct Vec : public vector<Vec<D - 1, T>> {
    static_assert(D >= 1, "Vector dimension must be greater than zero!");
                          template<typename... Args>
    Vec(int n = 0, Args... args) : vector<Vec<D - 1, T>>(n, Vec<D - 1, T>(args...)) {
    }
};
    template<typename T>
struct Vec<1, T> : public vector<T> {
    Vec(int n = 0, T val = T()) : vector<T>(n, val) {
    }
};
                    // Vec<2,lli>mat(n,n,1);
    #define print(a) for(auto p:a) cout<<p<<endl; cout<<endl;
    #define read(a) for(auto &p:a)cin>>p>>endl;
std::vector<bool> is_prime;
std::vector<lli> primes;
void sieve(lli n){is_prime.resize(n+2,true);primes.clear();lli p;for(p=2;p*p<=n;p++){if(is_prime[p]){lli i;for(i=p*p;i<=n;i+=p){is_prime[i]=false;}}}is_prime[0]=is_prime[1]=false;lli i;for(i=2;i<=n;i++){if(is_prime[i]){primes.eb(i);}}}
mll prime_factors(lli n){  mll s;lli i;lli tc=0;while(n%2==0){tc++;n/=2;}if(tc>0){s[2]=tc;}for(i=3;i<=sqrt(n);i+=2){tc=0;while(n%i==0){tc++;n/=i;}if(tc>0){s[i]=tc;}}if(n>2){s[n]+=1;}return s;}
std::vector<lli> fact_vec;
void fact_fun(lli n){fact_vec.resize(n+10);lli i;fact_vec[0]=1;for(i=1;i<=n+2;i++){fact_vec[i]=(fact_vec[i-1]*i)%MOD;}}
vll p2;
void power_2(lli n,lli m=MOD){ lli i;MOD=m;p2.eb(1);forr(i,0,n){p2.eb(fmult(p2.back(),2));}}
lli ncr(lli n,lli r){if(r>n)return 0;return fdiv(fact_vec[n],fmult(fact_vec[r],fact_vec[n-r]));}
vll spf;void sieve2(lli MAXN) { MAXN+=10;spf.resize(MAXN,0);spf[1] = 1; for (lli i=2; i<MAXN; i++) spf[i] = i;     for (lli i=4; i<MAXN; i+=2) spf[i] = 2; for (lli i=3; i*i<MAXN; i++) {         if (spf[i] == i) { for (lli j=i*i; j<MAXN; j+=i) {if (spf[j]==j) spf[j] = i; }} } } 

mll getFactorization(lli x) 
{ 
    mll ret; 
    while (x != 1){ 
        // ret.eb(spf[x]); 
        ret[spf[x]]++;
        x = x / spf[x]; 
    } return ret; 
}


class Sol{    
public:       
    lli n,k;
    vector<vpll>graph;
    vll vis;
    Sol(){      
        lli  i,j;   
        cin>>n>>k;
        vll a(n),b(n);
        cin>>a>>b;
        graph.resize(n);
        vis.resize(n);
        forr(i,0,n){
            a[i]--;
            graph[i].eb(mp(b[a[i]],a[i]));
        }               
        // print(graph);
        lli ans=-INF;             
        forr(i,0,n){
            vis.assign(n,false);
            vll cp;
            bool cyc=dfs(i,cp);
            lli sum=accumulate(all(cp),0ll);      
            lli len=cp.size();
            lli cur= sum* (k/len);
            lli cur2=0;            
            forr(j,0,k%len){
                cur+=cp[j];
            }
            forr(j,0,min(len,k)){
                cur2+=cp[j];
                ans=max(ans,cur2);
            }
            ans=max(ans,cur);
            ans=max(ans,cur2);
        }
        cout<<ans<<endl;
    }         
    bool dfs(lli src,vll &cp){
        if(vis[src]){
            return true;
        }
        vis[src]=1;        
        for(auto p:graph[src]){
            cp.eb(p.F);
            return dfs(p.S,cp);
        }
        return false;
    }

};


int main(){    
    lli i,j;    

            #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);   
    freopen("output.txt",  "w", stdout);
            #endif

    ios::sync_with_stdio(false);    
    cin.tie(0);


    lli ti;

    ti=1;
        // cin>>ti;       
    while(ti--){
        Sol sol;
    }

}