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//#pragma GCC optimize("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#pragma warning(disable:4786)
#pragma warning(disable:4996)
#include <random>
#include <chrono>
#include <ctime>
#include<list>
#include <numeric>
#include<bitset>
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<set>
#include<map>
#include<functional>
#include<string>
#include<cstring>
#include<cstdlib>
#include<queue>
#include<utility>
#include<fstream>
#include<sstream>
#include<cmath>
#include<stack>
#include<assert.h>
#include<unordered_map>
#include<unordered_set>
#include <array>
#include <complex>
using namespace std;

#define MEM(a, b) memset(a, (b), sizeof(a))
#define CLR(a) memset(a, 0, sizeof(a))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define ABS(X) ( (X) > 0 ? (X) : ( -(X) ) )
#define S(X) ( (X) * (X) )
#define SZ(V) (int )V.size()
#define FORN(i, n) for(int i = 0; i < n; i++)
#define FORAB(i, a, b) for(int i = a; i <= b; i++)
#define ALL(V) V.begin(), V.end()
#define IN(A, B, C)  ((B) <= (A) && (A) <= (C))
#define AIN(A, B, C) assert(IN(A, B, C))

typedef long long int LL;
//typedef __int128 LLL;
typedef long long LLL;

typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef pair<double, double> PDD;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef vector<PLL> VPL;
typedef vector<PII> VP;
typedef vector<double> VD;
typedef vector<vector<int>> VVI;
typedef vector<string> VS;
typedef long double ld;

#define MAXN 203
#define MAXN2 MAXN*MAXN
//#define MAXN 1006

const LL MOD = 1000000007;
//const LL MOD = 998244353;
//const LL INF = 2000000000000000001LL; //2e18 + 1

int n;
int tree[2][500005][2];
int root[2];
// root to leaf.
VI order[2];
// pull_left = pull from left to right.
// pull_right = pull from right to left.
LL pull_left[2][500005], pull_right[2][500005];
LL cum_pull_left[2][500005], cum_pull_right[2][500005];

int subtree_sz[2][500005];

inline LL add_reduce(LL x) {
	if (x >= MOD) return x - MOD;
	return x;
}

void solve(int ks) {
	scanf("%d", &n);
	for (int i = 0; i < 2; i++) {
		for (int j = 1; j <= n; j++) {
			int p;
			scanf("%d", &p);
			if (p == -1) {
				root[i] = j;
				continue;
			}
			tree[i][p][j > p] = j;
		}

		order[i].resize(n);
		int tail = 0, head = 1;
		order[i][0] = root[i];
		while (tail < n) {
			int u = order[i][tail++];
			for (int j = 0; j < 2; j++) {
				if (tree[i][u][j]) {
					order[i][head++] = tree[i][u][j];
				}
			}
		}

		for (int j = n - 1; j >= 0; j--) {
			int u = order[i][j];
			int lft = tree[i][u][0], rgt = tree[i][u][1];
			subtree_sz[i][u] += subtree_sz[i][lft] + subtree_sz[i][rgt] + 1;
			pull_left[i][u] = add_reduce(subtree_sz[i][lft] + cum_pull_right[i][lft]);
			pull_right[i][u] = add_reduce(subtree_sz[i][rgt] + cum_pull_left[i][rgt]);
			cum_pull_left[i][u] = add_reduce(pull_left[i][u] + cum_pull_left[i][rgt]);
			cum_pull_right[i][u] = add_reduce(pull_right[i][u] + cum_pull_right[i][lft]);
		}
	}

	LL ans = 0;
	queue<PII> Q;
	Q.push({ root[0], root[1] });
	while (!Q.empty()) {
		int u = Q.front().first, v = Q.front().second;
		Q.pop();
		if (u == 0 && v == 0) continue;
		ans = add_reduce(ans + ABS(u - v));

		if (u == v) {
			Q.push({ tree[0][u][0], tree[1][v][0] });
			Q.push({ tree[0][u][1], tree[1][v][1] });
			continue;
		}

		// Solve left.
		int orig_u = u, orig_v = v;
		int covered_u = u, covered_v = v;
		u = tree[0][u][0], v = tree[1][v][0];
		while (covered_u != covered_v) {
			if (covered_u < covered_v) {
				// progress v.
				ans = add_reduce(ans + pull_right[1][v]);
				covered_v = covered_v - 1 - subtree_sz[1][tree[1][v][1]];
				v = tree[1][v][0];
			}
			else {
				// progress u.
				ans = add_reduce(ans + pull_right[0][u]);
				covered_u = covered_u - 1 - subtree_sz[0][tree[0][u][1]];
				u = tree[0][u][0];
			}
		}
		Q.push({ u, v });

		// Solve right.
		u = orig_u, v = orig_v;
		covered_u = u, covered_v = v;
		u = tree[0][u][1], v = tree[1][v][1];
		while (covered_u != covered_v) {
			if (covered_u > covered_v) {
				// progress v.
				ans = add_reduce(ans + pull_left[1][v]);
				covered_v = covered_v + 1 + subtree_sz[1][tree[1][v][0]];
				v = tree[1][v][1];
			}
			else {
				// progress u.
				ans = add_reduce(ans + pull_left[0][u]);
				covered_u = covered_u + 1 + subtree_sz[0][tree[0][u][0]];
				u = tree[0][u][1];
			}
		}
		Q.push({ u, v });
	}
	printf("%lld\n", ans);
}

void gen() {
}

int main()
{
	double start_time = clock();
#ifdef LOCAL
	freopen("C:\\Home\\Contests\\F\\sample.in", "r", stdin);
	//	freopen("out.out", "w", stdout);
#endif

	gen();

	if (0) {
		int T;
		scanf("%d", &T);
		//AIN(T, 1, 5000);
		for (int ks = 1; ks <= T; ks++) {
			solve(ks);
			//if (ks % 1 == 0) fprintf(stderr, "%d done\n", ks);
		}
	}
	else {
		solve(0);
	}

	double end_time = clock();
	fprintf(stderr, "Time = %lf\n", (end_time - start_time) / CLOCKS_PER_SEC);

	return 0;
}