#include<bits/stdc++.h>

#define LL long long 
#define pb push_back
#define For(i,a,b) for(int i=a;i<=b;++i)
#define foR(i,a,b) for(int i=a;i>=b;--i)

const int N = 2e5 + 5;

using namespace std;
int siz[N],a[N],n,x;
vector<int> p[N];
int dfs(int x,int dep){
    siz[x]=0;
    for(int i:p[x])
    {
        siz[x]+=dfs(i,dep+1);
    }
    a[x]=siz[x]-dep-a[x];
    return siz[x]+1;
}
bool cmp(int x,int y){
    return x>y;
}
int main()
{
    scanf("%d",&n);
    For(i,1,n) scanf("%d",&a[i]);
    For(i,2,n){
        scanf("%d",&x);
        p[x].push_back(i);
    }
    dfs(1,0);
    sort(a+1,a+n+1,cmp);
    LL s=0;
    for(int i=1;i<=n;i+=2) s+=1ll*a[i];
    printf("%lld",s);
    return 0;
}