#include<bits/stdc++.h>
using namespace std;

#define cout cerr
#define rep(i,a,b) for(int i=(a);i<=(b);++i)#include<bits/stdc++.h>
using namespace std;

#define cout cerr
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)

typedef long long ll;
typedef pair<int,int> pii;
#define FR first
#define SE second
const ll inf=1e18;

inline void rd(int &x){
    x=0;char ch=getchar();int f=1;
    while(ch<'0'||ch>'9'){
        if(ch=='-')f=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9'){
        x=x*10+ch-'0';
        ch=getchar();
    }
    x*=f;
}
//是否解决 系数 类型

int n;
#define Maxn 400010
int a[Maxn];
ll F[Maxn][8];
int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
void add_edge(int s,int e){
    tot++;v[tot]=e;nxt[tot]=head[s];head[s]=tot;
}

int calc(int a,int b){
    int a1=(a/2)&1,a2=a/4;
    int b1=(b/2)&1,b2=b/4;
    if(a2==1&&b2==1)return -1;
    if(a2==0&&b2==0)return 0;
    if(a2==0&&b2==1&&a1!=b1)return 1;
    if(a2==1&&b2==0&&a1!=b1)return 2;
    return 0;
}

ll fjz[8];
void dfs(int u){
    rep(i,0,7)
    if(i!=1&&i!=3){
        int t=(i/2)&1;
        if(t==0)F[u][i]=a[u];
        else F[u][i]=-a[u];
    }else F[u][i]=-inf;
    for(int i=head[u];i;i=nxt[i]){
        int t=v[i];
        dfs(t);
        rep(j,0,7)fjz[j]=-inf;
        rep(c1,0,7)
            rep(c2,0,7){
                int cur=calc(c1,c2);
                if(cur==-1)continue;
                int ss=c2&1;
                if(cur==2)ss=1;
                if(ss==0)continue;
                if(cur==1)c1|=1;
                fjz[c1]=max(fjz[c1],F[u][c1]+F[t][c2]);
            }
        rep(j,0,7)F[u][j]=fjz[j];
    }
}

int main(){
    rd(n);
    rep(i,1,n)rd(a[i]);
    rep(i,2,n){
        int x;rd(x);add_edge(x,i);
    }
    dfs(1);ll Ans=-inf;
    dfs(1);
    rep(i,4,7)Ans=max(Ans,F[1][i]);
    printf("%lld\n",Ans);
    return 0;
}  
#define per(i,a,b) for(int i=(a);i>=(b);--i)

typedef long long ll;
typedef pair<int,int> pii;
#define FR first
#define SE second
const ll inf=1e18;

inline void rd(int &x){
    x=0;char ch=getchar();int f=1;
    while(ch<'0'||ch>'9'){
        if(ch=='-')f=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9'){
        x=x*10+ch-'0';
        ch=getchar();
    }
    x*=f;
}
//是否解决 系数 类型

int n;
#define Maxn 400010
int a[Maxn];
ll F[Maxn][8];
int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
void add_edge(int s,int e){
    tot++;v[tot]=e;nxt[tot]=head[s];head[s]=tot;
}

int calc(int a,int b){
    int a1=(a/2)&1,a2=a/4;
    int b1=(b/2)&1,b2=b/4;
    if(a2==1&&b2==1)return -1;
    if(a2==0&&b2==0)return 0;
    if(a2==0&&b2==1&&a1!=b1)return 1;
    if(a2==1&&b2==0&&a1!=b1)return 2;
    return 0;
}

ll fjz[8];
void dfs(int u){
    rep(i,0,7)
    if(i!=1&&i!=3){
        int t=(i/2)&1;
        if(t==0)F[u][i]=a[u];
        else F[u][i]=-a[u];
    }else F[u][i]=-inf;
    for(int i=head[u];i;i=nxt[i]){
        int t=v[i];
        dfs(t);
        rep(j,0,7)fjz[j]=-inf;
        rep(c1,0,7)
            rep(c2,0,7){
                int cur=calc(c1,c2);
                if(cur==-1)continue;
                int ss=c2&1;
                if(cur==2)ss=1;
                if(ss==0)continue;
                if(cur==1)c1|=1;
                fjz[c1]=max(fjz[c1],F[u][c1]+F[t][c2]);
            }
        rep(j,0,7)F[u][j]=fjz[j];
    }
}

int main(){
    freopen("ex_1.in","r",stdin);
    rd(n);
    rep(i,1,n)rd(a[i]);
    rep(i,2,n){
        int x;rd(x);add_edge(x,i);
    }
    dfs(1);ll Ans=-inf;
    dfs(1);
    rep(i,4,7)Ans=max(Ans,F[1][i]);
    printf("%lld\n",Ans);
    return 0;
}  

answer.code:5:18: error: '#' is not followed by a macro parameter
    5 | #define rep(i,a,b) for(int i=(a);i<=(b);++i)#include<bits/stdc++.h>
      |                  ^
answer.code:95:10: error: redefinition of ‘const ll inf’
   95 | const ll inf=1e18;
      |          ^~~
answer.code:16:10: note: ‘const ll inf’ previously defined here
   16 | const ll inf=1e18;
      |          ^~~
answer.code:97:13: error: redefinition of ‘void rd(int&)’
   97 | inline void rd(int &x){
      |             ^~
answer.code:18:13: note: ‘void rd(int&)’ previously defined here
   18 | inline void rd(int &x){
      |             ^~
answer.code:111:5: error: redefinition of ‘int n’
  111 | int n;
      |     ^
answer.code:32:5: note: ‘int n’ previously declared here
   32 | int n;
      |     ^
answer.code:113:5: error: redefinition of ‘int a [400010]’
  113 | int a[Maxn];
      |     ^
answer.code:34:5: note: ‘int a [400010]’ previously declared here
   34 | int a[Maxn];
      |     ^
answer.code:114:4: error: redefinition of ‘ll F [400010][8]’
  114 | ll F[Maxn][8];
      |    ^
answer.code:35:4: note: ‘ll F [400010][8]’ previously declared here
   35 | ll F[Maxn][8];
      |    ^
answer.code:115:5: error: redefinition of ‘int head [400010]’
  115 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |     ^~~~
answer.code:36:5: note: ‘int head [400010]’ previously declared here
   36 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |     ^~~~
answer.code:115:16: error: redefinition of ‘int v [400010]’
  115 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |                ^
answer.code:36:16: note: ‘int v [400010]’ previously declared here
   36 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |                ^
answer.code:115:24: error: redefinition of ‘int nxt [400010]’
  115 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |                        ^~~
answer.code:36:24: note: ‘int nxt [400010]’ previously declared here
   36 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |                        ^~~
answer.code:115:34: error: redefinition of ‘int tot’
  115 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |                                  ^~~
answer.code:36:34: note: ‘int tot’ previously defined here
   36 | int head[Maxn],v[Maxn],nxt[Maxn],tot=0;
      |                                  ^~~
answer.code:116:6: error: redefinition of ‘void add_edge(int, int)’
  116 | void add_edge(int s,int e){
      |      ^~~~~~~~
answer.code:37:6: note: ‘void add_edge(int, int)’ previously defined here
   37 | void add_edge(int s,int e){
      |      ^~~~~~~~
answer.code:120:5: error: redefinition of ‘int calc(int, int)’
  120 | int calc(int a,int b){
      |     ^~~~
answer.code:41:5: note: ‘int calc(int, int)’ previously defined here
   41 | int calc(int a,int b){
      |     ^~~~
answer.code:130:4: error: redefinition of ‘ll fjz [8]’
  130 | ll fjz[8];
      |    ^~~
answer.code:51:4: note: ‘ll fjz [8]’ previously declared here
   51 | ll fjz[8];
      |    ^~~
answer.code:131:6: error: redefinition of ‘void dfs(int)’
  131 | void dfs(int u){
      |      ^~~
answer.code:52:6: note: ‘void dfs(int)’ previously defined here
   52 | void dfs(int u){
      |      ^~~
answer.code:156:5: error: redefinition of ‘int main()’
  156 | int main(){
      |     ^~~~
answer.code:77:5: note: ‘int main()’ previously defined here
   77 | int main(){
      |     ^~~~
answer.code: In function ‘int main()’:
answer.code:157:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  157 |     freopen("ex_1.in","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~