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#include<stdio.h>
#include<cstring>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<bitset>
#include<utility>
#include<functional>
#include<iomanip>
#include<sstream>
#include<ctime>
#include<cassert>
using namespace std;
#define y0 y0z
#define y1 y1z
#define yn ynz
#define j0 j0z
#define j1 j1z
#define jn jnz
#define tm tmz
#define buli(x) (__builtin_popcountll(x))
#define bur0(x) (__builtin_ctzll(x))
#define bul2(x) (63-__builtin_clzll(x))
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fil(a,b) memset((a),(b),sizeof(a))
#define cl(a) fil(a,0)
#define siz(x) ((int)(x).size())
#define all(x) (x).begin(),(x).end()
#define foreach(it,a) for(__typeof((a).begin()) it=(a).begin();it!=(a).end();it++)
#define rep(i,a,b) for (int i=(a),_ed=(b);i<_ed;i++)
#define per(i,a,b) for (int i=(b)-1,_ed=(a);i>=_ed;i--)
#define forg(i,gu) for (int i=gu;~i;i=e[i].next)
#define pw(x) ((ll(1))<<(x))
#define upmo(a,b) (((a)=((a)+(b))%mo)<0?(a)+=mo:(a))
#define mmo(a,b) (((a)=1ll*(a)*(b)%mo)<0?(a)+=mo:(a))
void getre(){int x=0;printf("%d\n",1/x);}
void gettle(){int res=1;while(1)res<<=1;printf("%d\n",res);}
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vpii;
template<typename T,typename S>inline bool upmin(T&a,const S&b){return a>b?a=b,1:0;}
template<typename T,typename S>inline bool upmax(T&a,const S&b){return a<b?a=b,1:0;}
template<typename N,typename PN>inline N flo(N a,PN b){return a>=0?a/b:-((-a-1)/b)-1;}
template<typename N,typename PN>inline N cei(N a,PN b){return a>0?(a-1)/b+1:-(-a/b);}
template<typename N>N gcd(N a,N b){return b?gcd(b,a%b):a;}
template<typename N>inline int sgn(N a){return a>0?1:(a<0?-1:0);}
#if ( ( _WIN32 || __WIN32__ ) && __cplusplus < 201103L)
#define lld "%I64d"
#else
#define lld "%lld"
#endif
inline void gn(long long&x){
	int sg=1;char c;while(((c=getchar())<'0'||c>'9')&&c!='-');c=='-'?(sg=-1,x=0):(x=c-'0');
	while((c=getchar())>='0'&&c<='9')x=x*10+c-'0';x*=sg;
}
inline void gn(int&x){long long t;gn(t);x=t;}
inline void gn(unsigned long long&x){long long t;gn(t);x=t;}
inline void gn(double&x){double t;scanf("%lf",&t);x=t;}
inline void gn(long double&x){double t;scanf("%lf",&t);x=t;}
inline void gs(char *s){scanf("%s",s);}
inline void gc(char &c){while((c=getchar())>126 || c<33);}
inline void pc(char c){putchar(c);}
#ifdef JCVB
#define debug(...) fprintf(stderr, __VA_ARGS__)
#else
#define debug(...)
#endif
typedef long long ll;
typedef double db;
inline ll sqr(ll a){return a*a;}
inline db sqrf(db a){return a*a;}
const int inf=0x3f3f3f3f;
//const ll inf=0x3f3f3f3f3f3f3f3fll;
const db pi=3.14159265358979323846264338327950288L;
const db eps=1e-6;
const int mo=1e9+7;
//int qp(int a,ll b){int n=1;do{if(b&1)n=1ll*n*a%mo;a=1ll*a*a%mo;}while(b>>=1);return n;}

const int N = 511111;

int n;
int chd[2][N][2]={0};
int rt[2];
int par[2][N];
int sz[2][N]={0};
int f[2][N][2]={0};
int endpoint[2][N][2]={0};
int xia[2][N][2][20];
int prefix[2][N][2];



void dfs(int tid,int u) {
	if(u) {
		dfs(tid,chd[tid][u][0]);
		dfs(tid,chd[tid][u][1]);
		sz[tid][u]=1 + sz[tid][chd[tid][u][0]] +sz[tid][chd[tid][u][1]];

		rep(chid,0,2) {
			if(chd[tid][u][chid]) 
				endpoint[tid][u][chid]=endpoint[tid][ chd[tid][u][chid] ][chid];
			else
				endpoint[tid][u][chid]=u;
		}

		rep(dir,0,2) {
			f[tid][u][dir] = (0ll+ f[tid][chd[tid][u][dir]][dir] + f[tid][chd[tid][u][!dir]][!dir] + sz[tid][chd[tid][u][!dir]])%mo;
		}
	}
}

struct subtree {
	int tid;
	int rt;
	int lowrt;
	int ed;
	pair<int,subtree> findsubroot(int x,int dir) {//dir=0
		int a;
		subtree tre;
		tre.tid=tid;
		if(lowrt!=0 && x>=endpoint[tid][lowrt][0] && x<=endpoint[tid][lowrt][1]) {
			a=lowrt;
			//for (;chd[tid][a][dir] && x>=endpoint[tid][chd[tid][a][dir]][0] && 
						//x<=endpoint[tid][chd[tid][a][dir]][1]  ; 
							//a=chd[tid][a][dir]); // todo fix force
			for (int d=19;d>=0;d--) {
				int b = xia[tid][a][dir][d];
				if( b && x>=endpoint[tid][b][0] && x<=endpoint[tid][b][1]) a=b;
			}
			if(x==a) {
				tre.lowrt=tre.rt=chd[tid][a][dir];
				tre.ed=0;
			} else {
				tre.lowrt=chd[tid][a][dir];
				tre.rt = x + 2*dir -1;// dir==1: +1, dir==0: -1
				tre.ed = a;
			}
		} else {
			a=x;
			if(a!=ed) {
				tre.lowrt=lowrt;
				tre.rt = x + 2*dir -1;// dir==1: +1, dir==0: -1
				tre.ed=ed;
			} else {
				tre.lowrt=lowrt;
				tre.rt = lowrt;
				tre.ed=0;
			}
		}
		return mp(a,tre);
	}
	int sumanswer(int x) {
		int ans=0;
		if(lowrt!=0 && x>=endpoint[tid][lowrt][0] && x<=endpoint[tid][lowrt][1]) {
			int dir;
			if(x<rt)dir=1;
			else dir=0;

			if(lowrt==rt) {
				upmo(ans, prefix[tid][x][dir]-prefix[tid][lowrt][dir]);
			} else upmo(ans,prefix[tid][x][dir]-prefix[tid][par[tid][lowrt]][dir]);

			//for(; x!=rt ;x=par[tid][x]) {
			//	upmo(ans, f[tid][chd[tid][x][dir]][dir]+sz[tid][chd[tid][x][dir]]);
				//if(x==lowrt)break; //fix force
			//}
		}
		return ans;
	}
	subtree ch(int dir) {
		subtree tre;
		tre.tid=tid;
		if(ed==0) {
			tre.rt=tre.lowrt=chd[tid][rt][dir];
			tre.ed=0;
		} else {
			int chaindir;
			if(ed==rt && lowrt==0) {
				tre.rt=tre.lowrt=0;
				tre.ed=0;
			}else if (ed!=rt) {
				if(rt>ed) chaindir=0;
				else chaindir=1;
				if(dir!=chaindir) {
					tre.rt=tre.lowrt=tre.ed=0;
				} else {
					tre.lowrt=lowrt;
					tre.rt=rt+2*chaindir-1;
					tre.ed=ed;
				}
			}else {
				if(rt>lowrt)chaindir=0;
				else chaindir=1;
				if(dir!=chaindir) {
					tre.rt=tre.lowrt=tre.ed=0;
				} else {
					tre.lowrt=lowrt;
					tre.rt=lowrt;
					tre.ed=0;
				}
			}
		}
		return tre;
	}
};

int dis(vector<subtree> sub) {
	if(sub[0].rt==0 || sub[1].rt==0) return 0;//
	if(sub[0].rt==sub[1].rt) {
		int ans=0;
		vector<subtree> nex;
		nex.resize(2);
		rep(d,0,2) {
			nex[0] = sub[0].ch(d), nex[1] = sub[1].ch(d);
			upmo(ans, dis(nex));
		}
		return ans;
	}else if(sub[0].rt<sub[1].rt) {
		swap(sub[0],sub[1]);
	}

	int ans=sub[0].rt-sub[1].rt;

	int a[2];
	subtree tre[2];
	rep(sid,0,2) {
		pair<int,subtree> temp = sub[sid].findsubroot(sub[!sid].rt, sid);
		a[sid] = temp.first;
		tre[sid] = temp.second;
		upmo(ans, sub[sid].sumanswer(a[sid]));
	}
	vector<subtree> nex;
	nex.resize(2);
	rep(d,0,2) {
		nex[0] = tre[d], nex[1] = sub[!d].ch(d);
		upmo(ans, dis(nex));
	}
	return ans;
}

void dfs2(int tid,int u) {
	if(u) {
		rep(dir,0,2) {
			prefix[tid][u][dir] = (0ll + f[tid][chd[tid][u][dir]][dir] + sz[tid][chd[tid][u][dir]] + prefix[tid][par[tid][u]][dir])%mo;
		}
		dfs2(tid,chd[tid][u][0]);
		dfs2(tid,chd[tid][u][1]);
	}
}
void readtree(int tid) {
	rep(i,1,n+1) {
		gn(par[tid][i]);
		if(par[tid][i]==-1){
			par[tid][i]=0;
			rt[tid]=i;
		} else {
			if(par[tid][i]>i) chd[tid][par[tid][i]][0]=i;
			else chd[tid][par[tid][i]][1]=i;
		}
	}
	dfs(tid,rt[tid]);
	rep(dir,0,2) {
		rep(u,1,n+1)xia[tid][u][dir][0] = chd[tid][u][dir];
		rep(d,1,20) 
			rep(u,1,n+1)xia[tid][u][dir][d] = xia[tid][ xia[tid][u][dir][d-1] ][dir][d-1];
	}
	dfs2(tid,rt[tid]);
	// building
}
int main()
{
#ifdef JCVB
	//freopen("1.in","r",stdin);
	//freopen("1.out","w",stdout);
	int _time_jc=clock();
#endif
	gn(n);
	rep(tid,0,2) readtree(tid);

	vector<subtree> nex;
	nex.resize(2);
	nex[0] = (subtree) {0, rt[0], rt[0], 0};
	nex[1] = (subtree) {1, rt[1], rt[1], 0};
	printf("%d\n",dis(nex));
#ifdef JCVB
	debug("time: %d\n",int(clock()-_time_jc));
#endif
	return 0;
}