1 #include "cstdio"
 2 #include "stdlib.h"
 3 #include "iostream"
 4 #include "algorithm"
 5 #include "string"
 6 #include "cstring"
 7 #include "queue"
 8 #include "cmath"
 9 #include "vector"
10 #include "map"
11 #include "set"
12 #define db double
13 #define ll long long
14 #define inf 0x3f3f3f
15 using namespace std;
16 const int N=3e5+5;
17 const int mod=1e9+7;
18 #define rep(i,x,y) for(int i=x;i<=y;i++)
19 //char s[N],t[N];
20 db  pi=3.14;
21 //int s[N],w[N];
22 int a[N],b[N];
23 int pre[N];
24 int main()
25 {
26     int n;
27     while(scanf("%d",&n)==1){
28         for(int i=1;i<=n;i++){
29             scanf("%d",a+i);
30             a[i]-=i;
31         }
32         memset(pre,0, sizeof(pre));
33         for(int i=n;i>=1;i--) pre[i]=max(a[i],pre[i+1]);
34         for(int i=1;i<=n;i++) scanf("%d",&b[i]);
35         sort(b+1,b+n+1);
36         int ma=0;
37         ll ans=pre[b[1]];
38         for(int i=2;i<=n;i++){
39             ma=max(pre[b[1]]-n-1,pre[b[i]]);
40             ans=(ma+ans)%mod;
41 //            printf("%d\n",ma);
42         }
43         printf("%lld\n",ans);
44     }
45 
46 }