#include <bits/stdc++.h>

#define N 200007

#define ll long long

#define lson t[x].ls

#define rson t[x].rs

#define setIO(s) freopen(s".in","r",stdin)

using namespace std;

const int MM=1e7+5e6+20;

int edges,tot,n;

int hd[N],to[N<<1],nex[N<<1],rt[N],A[N],val[N];

struct node

{

    int ls,rs,sum;

}t[MM];

inline int newnode() { return ++tot; }

inline void add(int u,int v)

{

    nex[++edges]=hd[u],hd[u]=edges,to[edges]=v;

}

void update(int &x,int l,int r,int p,int v)

{

    if(!x)  x=newnode();

    t[x].sum+=v;

    if(l==r)    return ;

    int mid=(l+r)>>1;

    if(p<=mid)    update(lson,l,mid,p,v);

    else update(rson,mid+1,r,p,v);

}

int merge(int x,int y)

{

    if(!x||!y)    return x+y;

    int now=newnode();

    t[now].sum=t[x].sum+t[y].sum;

    t[now].ls=merge(t[x].ls,t[y].ls);

    t[now].rs=merge(t[x].rs,t[y].rs);

    return now;

}

int find(int x,int l,int r,int p)

{

    if(!x)   return 0;

    if(l==r)   return t[x].sum?l:0;

    int mid=(l+r)>>1;

    if(p<=mid)

    {

        return find(lson,l,mid,p);

    }

    else

    {

        int pp=find(rson,mid+1,r,p);

        if(!pp)    return find(lson,l,mid,p);

        else return pp;

    }

}

void dfs(int u,int ff)

{

    for(int i=hd[u];i;i=nex[i])

    {

        int v=to[i];

        dfs(v,u);

        rt[u]=merge(rt[u],rt[v]);

    }

    update(rt[u],0,n,val[u],1);

    int pos=find(rt[u],0,n,val[u]-1);

    if(pos)   update(rt[u],0,n,pos,-1);

}

int main()

{

    // setIO("input");

    int i,j;

    scanf("%d",&n);

    for(i=1;i<=n;++i)     scanf("%d",&val[i]), A[i]=val[i];

    sort(A+1,A+1+n);

    for(i=1;i<=n;++i)     val[i]=lower_bound(A+1,A+1+n,val[i])-A;

    for(i=2;i<=n;++i)

    {

        int ff;

        scanf("%d",&ff);

        add(ff,i);

    }

    dfs(1,0);

    printf("%d\n",t[rt[1]].sum);

    return 0;

}