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#pragma GCC optimize("Ofast")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define mp make_pair
#define eb emplace_back
#define pb push_back
#define e1 first
#define e2 second
#define uint unsigned int
#define ll long long
#define ull unsigned long long
#define ld long double
#define float long double
#define size(x) (int)x.size()
#define satori int testCases; cin>>testCases; while(testCases--)
#define fastio ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define all(r) begin(r),end(r)
#define time chrono::high_resolution_clock().now().time_since_epoch().count()
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
mt19937 rng(chrono::high_resolution_clock().now().time_since_epoch().count());
///////////////////
#define debug if(false)
///////////////////

const int MAXN=5e5+10,inf=1e9+2137;
const ll mod=1e9+7;

int ogson[2][MAXN],anson[2][MAXN];
ll result=0;
int interval_count=0;
vector<int> interval_root={0};
vector<int> interval_par={0};
vector<int> interval_lson={0};
vector<int> interval_rson={0};
vector<int> interval_lbound={0};
vector<int> interval_rbound={0};
set<pair<int,int>> left_ends;

int my_interval(int x){
	auto xd=left_ends.upper_bound(mp(x,inf));
	xd--;
	return (*xd).e2;
}

void union_subtree(int interval_id){
	int par_id=interval_par[interval_id];
	if(interval_root[interval_id]<interval_root[par_id]){
		if(interval_rson[interval_id])
			union_subtree(interval_rson[interval_id]);
		if(interval_lson[interval_id])
			union_subtree(interval_lson[interval_id]);
		result+=abs(interval_root[interval_id]-interval_rbound[interval_id]);
		left_ends.erase(mp(interval_lbound[par_id],par_id));
		left_ends.erase(mp(interval_lbound[interval_id],interval_id));
		interval_lbound[par_id]=interval_lbound[interval_id];
		interval_lson[par_id]=interval_lson[interval_id];
		if(interval_lson[par_id])
			interval_par[interval_lson[interval_id]]=par_id;
		left_ends.insert(mp(interval_lbound[par_id],par_id));
	}
	else{
		if(interval_rson[interval_id])
			union_subtree(interval_rson[interval_id]);
		if(interval_lson[interval_id])
			union_subtree(interval_lson[interval_id]);
		result+=abs(interval_root[interval_id]-interval_lbound[interval_id]);
		left_ends.erase(mp(interval_lbound[interval_id],interval_id));
		interval_rson[par_id]=interval_rson[interval_id];
		if(interval_rson[par_id])
			interval_par[interval_rson[interval_id]]=par_id;
		interval_rbound[par_id]=interval_rbound[interval_id];
	}
}

void union_up(int interval_id){
	int par_id=interval_par[interval_id];
	if(interval_root[interval_id]<interval_root[par_id]){
		if(interval_rson[interval_id])
			union_subtree(interval_rson[interval_id]);
		result+=abs(interval_root[interval_id]-interval_rbound[interval_id]);
		left_ends.erase(mp(interval_lbound[par_id],par_id));
		left_ends.erase(mp(interval_lbound[interval_id],interval_id));	
		interval_lbound[par_id]=interval_lbound[interval_id];
		interval_lson[par_id]=interval_lson[interval_id];
		if(interval_lson[par_id])
			interval_par[interval_lson[interval_id]]=par_id;
		left_ends.insert(mp(interval_lbound[par_id],par_id));
	}
	else{
		if(interval_lson[interval_id])
			union_subtree(interval_lson[interval_id]);
		result+=abs(interval_root[interval_id]-interval_lbound[interval_id]);
		left_ends.erase(mp(interval_lbound[interval_id],interval_id));
		interval_rson[par_id]=interval_rson[interval_id];
		if(interval_rson[par_id])
			interval_par[interval_rson[interval_id]]=par_id;
		interval_rbound[par_id]=interval_rbound[interval_id];
	}
}

void solve(int anroot){
	int interval_id=-1,par_id=-1;
	while(true){
		interval_id=my_interval(anroot);
		par_id=interval_par[interval_id];
		if(!par_id)
			break;
		union_up(interval_id);
	}
	result+=abs(interval_root[interval_id]-anroot);
	interval_root[interval_id]=anroot;
	left_ends.erase(mp(interval_lbound[interval_id],interval_id));
	if(interval_lbound[interval_id]==anroot){
		if(interval_lson[interval_id]){
			interval_par[interval_lson[interval_id]]=0;
			if(anson[0][anroot])
				solve(anson[0][anroot]);
		}
	}
	else{
		interval_count++;
		left_ends.insert(mp(interval_lbound[interval_id],interval_count));
		interval_root.eb(anroot-1);
		interval_par.eb(0);
		interval_rson.eb(0);
		interval_lbound.eb(interval_lbound[interval_id]);
		interval_rbound.eb(anroot-1);
		if(interval_lson[interval_id])
			interval_lson.eb(interval_lson[interval_id]),interval_par[interval_lson[interval_id]]=interval_count;
		else
			interval_lson.eb(0);
		if(anson[0][anroot])
			solve(anson[0][anroot]);
	}
	if(interval_rbound[interval_id]==anroot){
		if(interval_rson[interval_id]){
			interval_par[interval_rson[interval_id]]=0;
			if(anson[1][anroot])
				solve(anson[1][anroot]);
		}
	}
	else{
		interval_count++;
		left_ends.insert(mp(anroot+1,interval_count));
		interval_root.eb(anroot+1);
		interval_par.eb(0);
		interval_lson.eb(0);
		interval_lbound.eb(anroot+1);
		interval_rbound.eb(interval_rbound[interval_id]);
		if(interval_rson[interval_id])
			interval_rson.eb(interval_rson[interval_id]),interval_par[interval_rson[interval_id]]=interval_count;
		else
			interval_rson.eb(0);
		if(anson[1][anroot])
			solve(anson[1][anroot]);
	}
}

void make_intervals(int root_par,int root){
	int left_bound=root,right_bound=root;
	while(ogson[0][left_bound]&&!ogson[1][ogson[0][left_bound]])
		left_bound=ogson[0][left_bound];
	while(ogson[1][right_bound]&&!ogson[0][ogson[1][right_bound]])
		right_bound=ogson[1][right_bound];
	interval_count++;
	interval_root.eb(root);
	interval_par.eb(root_par);
	left_ends.insert(mp(left_bound,interval_count));
	interval_lson.eb(0);
	interval_rson.eb(0);
	interval_lbound.eb(left_bound);
	interval_rbound.eb(right_bound);
	if(root<interval_root[root_par])
		interval_lson[root_par]=interval_count;
	else
		interval_rson[root_par]=interval_count;
	int interval_num=interval_count;
	if(ogson[0][left_bound])
		make_intervals(interval_num,ogson[0][left_bound]);
	if(ogson[1][right_bound])
		make_intervals(interval_num,ogson[1][right_bound]);
}

int32_t main()
{
	fastio;
	int n,par,ogroot=-1,anroot=-1;
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>par;
		if(par==-1){
			ogroot=i;
			continue;
		}
		if(par>i)
			ogson[0][par]=i;
		else
			ogson[1][par]=i;
	}
	for(int i=1;i<=n;i++){
		cin>>par;
		if(par==-1){
			anroot=i;
			continue;
		}
		if(par>i)
			anson[0][par]=i;
		else
			anson[1][par]=i;
	}
	make_intervals(0,ogroot);
	solve(anroot);
	result%=mod;
	cout<<result<<'\n';
}