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#include <bits/stdc++.h>
#define MP make_pair
#define PB push_back
#define int long long
#define st first
#define nd second
#define rd third
#define FOR(i, a, b) for(int i =(a); i <=(b); ++i)
#define RE(i, n) FOR(i, 1, n)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define REP(i, n) for(int i = 0;i <(n); ++i)
#define VAR(v, i) __typeof(i) v=(i)
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define __builtin_ctz __builtin_ctzll
#define __builtin_clz __builtin_clzll
#define __builtin_popcount __builtin_popcountll
using namespace std;
template<typename TH> void _dbg(const char* sdbg, TH h) { cerr<<sdbg<<"="<<h<<"\n"; }
template<typename TH, typename... TA> void _dbg(const char* sdbg, TH h, TA... t) {
  while(*sdbg != ',') { cerr<<*sdbg++; } cerr<<"="<<h<<","; _dbg(sdbg+1, t...);
}
#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#define debugv(x) {{cerr <<#x <<" = "; FORE(itt, (x)) cerr <<*itt <<", "; cerr <<"\n"; }}
#else
#define debug(...) (__VA_ARGS__)
#define debugv(x)
#define cerr if(0)cout
#endif
#define next ____next
#define prev ____prev
#define left ____left
#define hash ____hash
typedef long long ll;
typedef long double LD;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VLL;
typedef vector<pair<int, int> > VPII;
typedef vector<pair<ll, ll> > VPLL;

template<class C> void mini(C&a4, C b4){a4=min(a4, b4); }
template<class C> void maxi(C&a4, C b4){a4=max(a4, b4); }
template<class T1, class T2>
ostream& operator<< (ostream &out, pair<T1, T2> pair) { return out << "(" << pair.first << ", " << pair.second << ")";}
template<class A, class B, class C> struct Triple { A first; B second; C third;
  bool operator<(const Triple& t) const { if (st != t.st) return st < t.st; if (nd != t.nd) return nd < t.nd; return rd < t.rd; } };
template<class T> void ResizeVec(T&, vector<int>) {}
template<class T> void ResizeVec(vector<T>& vec, vector<int> sz) {
  vec.resize(sz[0]); sz.erase(sz.begin()); if (sz.empty()) { return; }
  for (T& v : vec) { ResizeVec(v, sz); }
}
typedef Triple<int, int, int> TIII;
template<class A, class B, class C>
ostream& operator<< (ostream &out, Triple<A, B, C> t) { return out << "(" << t.st << ", " << t.nd << ", " << t.rd << ")"; }
template<class T> ostream& operator<<(ostream& out, vector<T> vec) { out<<"("; for (auto& v: vec) out<<v<<", "; return out<<")"; }
template<class T> ostream& operator<<(ostream& out, set<T> vec) { out<<"("; for (auto& v: vec) out<<v<<", "; return out<<")"; }
template<class L, class R> ostream& operator<<(ostream& out, map<L, R> vec) { out<<"("; for (auto& v: vec) out<<v<<", "; return out<<")"; }

struct Node {
  int left, right;
  Node() {
    left = -1;
    right = -1;
  }
};
typedef vector<Node> Tree;
// struct Tree {
//   vector<Node> nodes;
// };

// int signum(int x) {
//   if (x > 0) { return 1; }
//   if (x < 0) { return -1; }
//   return 0;
// }


int Right(Tree* T, int root, int x, int y);

int Left(Tree* T, int root, int x, int y) {
  if (root == -1) { return 0; }
  return Left(T, (*T)[root].left, x, root - 1) + Right(T, (*T)[root].right, root + 1, y) + y - root;
}

int Right(Tree* T, int root, int x, int y) {
  if (root == -1) { return 0; }
  return Left(T, (*T)[root].left, x, root - 1) + Right(T, (*T)[root].right, root + 1, y) + root - x ;
}

void Deb(Tree* T, int root) {
  if (root == -1) { cerr<<"."; return; }
  cerr<<"(";
  Deb(T, (*T)[root].left);
  cerr<<", "<<root<<", ";
  Deb(T, (*T)[root].right);
  cerr<<")";
}
int f(Tree* A, int whA, int A_path_beg, int A_path_end, Tree* B, int whB, int B_path_beg, int B_path_end, int path_dir) {
//   Deb(A, whA);
//   cerr<<endl;
//   Deb(B, whB);
//   cerr<<endl;
  //debug(whA, A_path_beg, A_path_end, whB, B_path_beg, B_path_end, path_dir);
//   int sA = signum(A_path_end - A_path_beg); 
//   if (sA && sA != path_dir) {
//     A_path_beg = -1;
//     A_path_end = -1;
//   }
//   int sB = signum(B_path_end - B_path_beg);
//   if (sB && sB != path_dir) {
//     B_path_beg = -1;
//     B_path_end = -1;
//   }
//   
//   if (whA == -1 && A_path_beg == -1) {
//     assert(whB == -1 && B_path_beg == -1);
//     return 0;
//   }
  
  if (A_path_end != -1 && B_path_end != -1) { // chce skrocic czesc wspolna sciezek
    assert(A_path_end == B_path_end);
    if (A_path_beg == B_path_beg) {
      return f(A, whA, -1, -1, B, whB, -1, -1, 0);
    }
    if (path_dir == -1) { // korzen najwiekszy i maleje w dol
      if (A_path_beg > B_path_beg) {
        return f(A, whA, -1, -1, B, whB, B_path_beg, A_path_beg - 1, -1);
      } else {
        return f(A, whA, A_path_beg, B_path_beg - 1, B, whB, -1, -1, -1);
      }
    } else {
      if (A_path_beg < B_path_beg) {
        return f(A, whA, -1, -1, B, whB, B_path_beg, A_path_beg + 1, 1);
      } else {
        return f(A, whA, A_path_beg, B_path_beg + 1, B, whB, -1, -1, 1);
      }
    }
  }
  if (whB == -1) {
    swap(A, B);
    swap(whA, whB);
    swap(A_path_beg, B_path_beg);
    swap(A_path_end, B_path_end);
  }
  if (whA == -1) {
    if (A_path_beg == -1) { return 0; }
    if (path_dir == -1) {
      int L = Left(B, whB, A_path_beg, A_path_end);
      debug(L);
      return L;
    } else {
      int R = Right(B, whB, A_path_end, A_path_beg);
      debug(R);
      return R;
    }
  }
  int rootA = whA, rootB = whB;
  if (A_path_end != -1) { rootA = A_path_end; }
  if (B_path_end != -1) { rootB = B_path_end; }
  debug(rootA, rootB);
  if (rootA > rootB) {
    swap(A, B);
    swap(whA, whB);
    swap(rootA, rootB);
    swap(A_path_beg, B_path_beg);
    swap(A_path_end, B_path_end);
  }
  //debug(
  int diff = rootB - rootA;
  debug(diff);
  if (A_path_end == -1 && B_path_end == -1) { // nie ma zadnych sciezek
    if (rootA == rootB) {
      return f(A, (*A)[whA].left,  -1, -1, B, (*B)[whB].left,  -1, -1, 0) +
             f(A, (*A)[whA].right, -1, -1, B, (*B)[whB].right, -1, -1, 0);
    }
    return diff + f(A, (*A)[whA].left, rootA, rootB - 1, B, (*B)[whB].left, -1, -1, -1) + 
        f(A, (*A)[whA].right, -1, -1, B, (*B)[whB].right, rootB, rootA + 1, 1);
  } else {
    if (rootA == rootB) {
      if ((A_path_end == -1) != (path_dir == -1)) {
        swap(A, B);
        swap(whA, whB);
        swap(rootA, rootB);
        swap(A_path_beg, B_path_beg);
        swap(A_path_end, B_path_end);
      }
    }
    if (A_path_end == -1) { // jest sciezka w prawym
      assert(path_dir == -1);
      int e1 = Right(A, (*A)[whA].right, rootA + 1, rootB);
      int e2 = f(A, (*A)[whA].left, rootA, rootB, B, whB, B_path_beg, B_path_end, path_dir);
      debug(diff, e1, e2);
      return diff + e1 + e2;
           
    } else {// jest sciezka w lewym
      assert(B_path_end == -1);
      assert(path_dir == 1);
      return diff + Left(B, (*B)[whB].left, rootA, rootB - 1) +
          f(A, whA, A_path_beg, A_path_end, B, (*B)[whB].right, rootB, rootA, path_dir);
    }
  }
}
pair<Tree, int> ReadTree(int n) {
  vector<Node> nodes(n + 2);
  int root = -1;
  RE (i, n) {
    int par;
    cin>>par;
    if (par == -1) {
      root = i;
    } else {
      if (par < i) {
        nodes[par].right = i;
      } else {
        nodes[par].left = i;
      }
    }
  }
  return {Tree{nodes}, root};
}
    
int32_t main() {

  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  cerr << fixed << setprecision(10);
  cin.tie(0);
  //double beg_clock = 1.0 * clock() / CLOCKS_PER_SEC;
  
  int n;
  cin>>n;
  pair<Tree, int> t1 = ReadTree(n);
  pair<Tree, int> t2 = ReadTree(n);
  debug(n);
  const int P = 1e9 + 7;
  cout<<f(&t1.st, t1.nd, -1, -1, &t2.st, t2.nd, -1, -1, 0) % P<<endl;
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  return 0;
}