#include<iostream>
#include<cstdio>
#include<vector>
#define N 5000
using namespace std;
const long long inf=(long long)(1e18);
int read()
{
	char c=0;
	int sum=0,f=1;
	while (c!='-'&&(c<'0'||c>'9')) c=getchar();
	if (c=='-') c=getchar(),f=-1;
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum*f;
}
int n,s,w[N+1],p[N+1],fa[N+1],a[N+1];
long long dp[N+1][3],ans;
vector<int>E[N+1];
bool used[N+1];
void dfs(int x)
{
	long long res;
	for (int op=1;op<=2;++op) dp[x][op]=w[x]*(op==1)-p[x]*op;
	used[x]=1;
	for (int i=0;i<E[x].size();++i)
		if (!used[E[x][i]])
		{
			fa[E[x][i]]=x,dfs(E[x][i]);
			for (int op=1;op<=2;++op)
			{
				res=0;
				for (int opt=1;opt<=op;++opt) res=max(res,dp[E[x][i]][opt]);
				dp[x][op]+=res;
			}
		}
	return;
}
int main()
{
	vector<int>sp;
	n=read(),s=read();
	for (int i=1;i<=n;++i) w[i]=read();
	for (int i=1;i<=n;++i) p[i]=read();
	for (int i=1;i<=n;++i) a[i]=read(),E[a[i]].push_back(i);
	dfs(s);
	if (a[a[s]]!=s) printf("%lld\n",max(dp[s][1],dp[s][2])+p[s]);
	else
	{
		ans=dp[s][1]-p[s];
		for (int i=0;i<E[s].size();++i)
			if (E[s][i]!=a[s])
				sp.push_back(E[s][i]);
		E[s]=sp,dfs(s),printf("%lld\n",max(dp[s][1],dp[s][2])-p[s]);
	}
	return 0;
}