#include<bits/stdc++.h>

using namespace std;

typedef long long LL;

const int N=3e5+;

const int mod=1e9+;

int n;

int a[N],b[N],c[N];

int main()

{

    while(~scanf("%d",&n))

    {

        for(int i=;i<=n;i++) scanf("%d",&a[i]);

        for(int i=;i<=n;i++) scanf("%d",&b[i]);

        sort(b+,b++n);

        c[n]=a[n]-n;

        for(int i=n-;i>;i--) c[i]=max(c[i+],a[i]-i);

        //c[i]:  max{a[j]-j| i<=j<=n}

        LL ans=;

        int ma=-mod;

        //ma: max{a[j]-j| n<j<n+i

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

        {

            int t=max(c[b[i]],ma);    //t: a[n+i]

            ma=max(ma,t-(n+i));        //a[n+i] in,update ma

            ans=(ans+t)%mod;

        }

        printf("%lld\n",ans);

    }

}