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#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> II;

#define INFTY 2000000000
#define MOD 1000000007
#define DEBUG(s,x) cerr << s << ": " << x << "\n";

#define VI vector<int>

#define LEFT 0
#define RIGHT 1

struct edge {
  VI vert;
  int begin, end;
  int child;
};

vector<VI> a_child, b_child;
VI a_parent, b_parent;
VI a_child_side, b_child_side;
int a_root, b_root;
int n;
vector<edge*> edge_to_parent;
vector<edge*> long_edge;
VI offset;    

void print_vec(VI & v)
{
  for (auto &e : v)
    cerr << e << " ";
  cerr << "\n";
}

void read_tree(vector<VI> &child, VI &parent, VI &child_side, int &root)
{
  for (int i=0; i<n; i++)
    child.push_back(VI(2,-1));
    
  parent.resize(n);  
  child_side.resize(n);  

  for (int i=0; i<n; i++)
    {
      int p;
      cin >> p;
      if (p != -1)
        p--;
      else
        root = i;  
      parent[i] = p;
      if (p != -1)
        if (i < p)
        {
          child[p][LEFT] = i;
          child_side[i] = LEFT;
        }  
        else
        {
          child[p][RIGHT] = i;
          child_side[i] = RIGHT;
        }  
    }
}

void compress_a (int v)
{
  int p = a_parent[v];
  for (int side : {LEFT,RIGHT})
    if (a_child[v][side] != -1)
    {
        compress_a(a_child[v][side]);
        if (p != -1 && 
            a_child[v][1-side] == -1  &&
            a_child_side[v] == side)
        {
          int ch = a_child[v][side]; 
          
          edge_to_parent[ch]->vert.push_back(v);
          offset[v] = edge_to_parent[ch]->vert.size()-1;
          long_edge[v] = edge_to_parent[ch];
             
          a_child [p][side] = ch;
          a_parent[ch] = p;
        }    
    } 
}

/*
void shallow_compress (int v)
{
  if a_child[v][LEFT] == -1
    side = LEFT;
  else
    if a_child[v][RIGHT] == -1
      side = RIGHT;
    else
      return;
      
  VI to_add;
  int x = v;    
  while (a_child[x][side] == -1 && a_child[x][1-side] != -1)
  {
    to_add.push_back(x);
    x = a_child[x][1-side];
  }
  int x = a_child[x][1-side];
  
  sort(to_add.begin(), to_add.end());
  
  for (auto & e : to_add)
  {
    edge_to_parent[x]->vert
  }
      
}
*/

// dekompresuje ścieżkę (długą krawędź) od v do ojca.
// jeśli w==-1 to oddziela najwyższy wierzchołek na ścieżce
// wpp oddziela w od ojca w.
void decompress_a (int v, int w = -1)
{
  if (v == -1)
    return; // no node
    
  //cerr << "decompress(" << v << (w == -1 ? "" : ", " + to_string(w)) << ")\n";   
    
  int p = a_parent[v]; 

  if (p == -1)
    return; // korzeń: nie ma krawędzi wzwyż
 
/*    
  cerr << "parent(v) = " << p << "\n";  

  cerr << "edge_to_parent[v]->begin = " << edge_to_parent[v]->begin << "\n";  
  cerr << "edge_to_parent[v]->end = " << edge_to_parent[v]->end << "\n";  
*/

  if (edge_to_parent[v]->begin == edge_to_parent[v]->end)
    return; // edge v->parent is not compressed
    
  int side = a_child_side[v];
  
  if (w == -1)
    if (side == LEFT)
      w = edge_to_parent[v]->vert[edge_to_parent[v]->end-1];
    else
      w = edge_to_parent[v]->vert[edge_to_parent[v]->begin];
      
//  cerr << "w = " << w << "\n";    
      
  if (side == LEFT) // większe od w idą do edge_to_parent[w]
     if (offset[w] - edge_to_parent[v]->begin >= edge_to_parent[v]->end - offset[w] - 1) // przenosimy końcówkę do w bo krótsza
     {
//       cerr << "Case A\n";
       for (int i=offset[w]+1; i<edge_to_parent[v]->end; ++i)
       {
         edge_to_parent[w]->vert.push_back(edge_to_parent[v]->vert[i]);
         long_edge[edge_to_parent[v]->vert[i]] = edge_to_parent[w];
         offset[edge_to_parent[v]->vert[i]] = edge_to_parent[w]->vert.size()-1;
       }  
       edge_to_parent[w]->begin=0;
       edge_to_parent[w]->end=edge_to_parent[w]->vert.size();
       edge_to_parent[v]->end = offset[w];
     }
     else
     {
       // przenosimy prefiks do v, końcówka wrzucona do w.
//       cerr << "Case B\n";
       swap(edge_to_parent[w], edge_to_parent[v]);
       for (int i=edge_to_parent[w]->begin; i<offset[w]; ++i)
       {
         edge_to_parent[v]->vert.push_back(edge_to_parent[w]->vert[i]);
         long_edge[edge_to_parent[w]->vert[i]] = edge_to_parent[v];
         offset[edge_to_parent[w]->vert[i]] = edge_to_parent[v]->vert.size()-1;
       }  
       edge_to_parent[v]->begin=0;
       edge_to_parent[v]->end=edge_to_parent[v]->vert.size();
       edge_to_parent[w]->begin = offset[w]+1;
     }
  else // side == RIGHT; mniejsze od w idą do edge_to_parent[w]
     if (offset[w] - edge_to_parent[v]->end - 1 >= offset[w] - edge_to_parent[v]->begin) // przenosimy prefix do w bo krótszy
     {
//       cerr << "Case C\n";
       for (int i=edge_to_parent[v]->begin; i<offset[w]; ++i)
       {
         edge_to_parent[w]->vert.push_back(edge_to_parent[v]->vert[i]);
         long_edge[edge_to_parent[v]->vert[i]] = edge_to_parent[w];
         offset[edge_to_parent[v]->vert[i]] = edge_to_parent[w]->vert.size()-1;
       }  
       edge_to_parent[w]->begin=0;
       edge_to_parent[w]->end=edge_to_parent[w]->vert.size();
       edge_to_parent[v]->begin = offset[w]+1;
     }
     else
     {
       // przenosimy końcówkę do v, prefix wrzucony do w.
//       cerr << "Case D\n";
       swap(edge_to_parent[w], edge_to_parent[v]);
       for (int i=offset[w]+1; i<edge_to_parent[w]->end; ++i)
       {
         edge_to_parent[v]->vert.push_back(edge_to_parent[w]->vert[i]);
         long_edge[edge_to_parent[w]->vert[i]] = edge_to_parent[v];
         offset[edge_to_parent[w]->vert[i]] = edge_to_parent[v]->vert.size()-1;
       }  
//       cerr << "after loop\n";
       edge_to_parent[v]->begin=0;
       edge_to_parent[v]->end=edge_to_parent[v]->vert.size();
       edge_to_parent[w]->end = offset[w];
     }
       
  edge_to_parent[v]->child = v;
  edge_to_parent[w]->child = w;
  long_edge[v]=edge_to_parent[v];
  long_edge[w]=edge_to_parent[w];
  
  a_child[p][side] = w;
  a_parent[w]=p;
  a_child[w][side] = v;
  a_child[w][1-side] = -1;
  a_parent[v]=w;
  a_child_side[w] = side;
  
  
/*
  DEBUG("edge_to_parent[v]->begin",edge_to_parent[v]->begin)
  DEBUG("edge_to_parent[v]->end",edge_to_parent[v]->end)
  DEBUG("edge_to_parent[w]->begin",edge_to_parent[w]->begin)
  DEBUG("edge_to_parent[w]->end",edge_to_parent[w]->end)
*/
}

void rotate (int v)
{
  //DEBUG("rotate (",v)

  if (a_child[v][1-a_child_side[v]] != -1)
  {
    cout << -1 << "\n";
    exit(0);
  }
  
  int w = a_parent[v];
  
  assert(w != -1);
  
  int p = a_parent[w];
  
  if (p != -1)
    a_child[p][a_child_side[w]] = v;
  a_parent[v] = p;
  a_parent[w] = v;
  a_child[v][1-a_child_side[v]] = w;
  a_child[w][a_child_side[v]] = -1;
  
  int side = a_child_side[v];
  a_child_side[v] = a_child_side[w];
  a_child_side[w] = 1-side;   
  
  swap(edge_to_parent[v], edge_to_parent[w]);
  edge_to_parent[v]->child = v; 
  edge_to_parent[w]->child = w; 
}

int transform (int v_a, int v_b)
{
  if (v_a == -1)
    return 0;
    
//  cerr << "transform(" << v_a << ", " << v_b << ")\n";  
    
  int p = a_parent[v_a];  
    
  if (long_edge[v_b]->child != v_b)
    decompress_a (long_edge[v_b]->child, v_b);
//  else
//    cerr << "no decompress\n";

  int num_rot = 0;
      
  while (a_parent[v_b] != p)  
  {
//    cerr << "a_parent[v_b] == " << a_parent[v_b] << " != " << p << "\n";
    num_rot += edge_to_parent[v_b]->vert.size()+1;
    rotate (v_b);
  }

//  cerr << "left child after rotations: " << a_child[v_b][LEFT] << "\n";
//  cerr << "right child after rotations: " << a_child[v_b][RIGHT] << "\n";

  decompress_a (a_child[v_b][LEFT]); 
  decompress_a (a_child[v_b][RIGHT]); 

//  cerr << "left child after rotations and decompress: " << a_child[v_b][LEFT] << "\n";
//  cerr << "right child after rotations and decompress: " << a_child[v_b][RIGHT] << "\n";

  return (num_rot + (transform (a_child[v_b][LEFT], b_child[v_b][LEFT]) + transform (a_child[v_b][RIGHT], b_child[v_b][RIGHT])) % MOD) % MOD;
}

int main()
{
    std::ios::sync_with_stdio(0);

    int i, j, k;

    cin >> n;

    read_tree(a_child, a_parent, a_child_side, a_root);
    read_tree(b_child, b_parent, b_child_side, b_root);
    
    for (i=0; i<n; i++)
    {
      edge * e = new edge();
      e->child = i;
      edge_to_parent.push_back(e);
      long_edge.push_back(e);
      offset.push_back(-1);
    }  
    
    compress_a (a_root);
    
    for (auto e : edge_to_parent)
    {
      e->begin = 0;
      e->end = e->vert.size();
      sort(e->vert.begin(), e->vert.end());
    }

/*
    cerr << a_child[a_root][LEFT] << "\n";
    int cc = a_child[a_root][LEFT];
    print_vec( edge_to_parent[cc]->vert);
    cerr <<  edge_to_parent[cc]->begin << " " << edge_to_parent[cc]->end << "\n"; 
*/

    cout << transform (a_root, b_root) << "\n";

    return 0;
}