using System;
using System.Collections.Generic;

class Program
{
  Scanner cin;

  int N;
  List<int>[] g;
  int[] sub;
  int[,] dp;
  

  void rec(int idx, int par)
  {
    int[] dp2 = { 0, 0, 0 };
    foreach(var to in g[idx])
    {
      if (to == par) continue;
      rec(to, idx);
      sub[idx] += sub[to];

      int[] dp3 = { 10101010, 10101010, 10101010 };
      for (int i = 0; i < 3; i++)
      {
        for(int j = 0; i + j < 3; j++)
        {
          dp3[i + j] = Math.Min(dp3[i + j], dp2[i] + dp[to, j] + (sub[to] + j) % 2);
        }
      }
      for (int i = 0; i < 3; i++)
      {
        dp2[i] = dp3[i];
      }
    }
    for(int i = 0; i < 3; i++)
    {
      dp[idx, i] = dp2[i];
    }
  }

  void myon()
  {
    cin = new Scanner();

    N = cin.nextInt();

    g = new List<int>[N];

    for(int i = 0; i < N; i++)
    {
      g[i] = new List<int>();
    }
    for(int i = 1; i < N; i++)
    {
      int a = cin.nextInt() - 1;
      int b = cin.nextInt() - 1;
      g[a].Add(b);
      g[b].Add(a);
    }
    sub = new int[N];
    for(int i = 1; i < N; i++)
    {
      int a = cin.nextInt() - 1;
      int b = cin.nextInt() - 1;
      sub[a] = 1 - sub[a];
      sub[b] = 1 - sub[b];
    }
    dp = new int[N, 3];
    rec(0, -1);
    Console.WriteLine(dp[0, 2] + (N - 1));
  }

  static void Main(string[] args)
  {
    new Program().myon();
  }
}

class Scanner
{
  string[] s;
  int i;
  readonly char[] cs = new char[] { ' ' };

  public Scanner()
  {
    s = new string[0];
    i = 0;
  }

  public string next()
  {
    if (i < s.Length) return s[i++];
    string st = Console.ReadLine();
    while (st == "") st = Console.ReadLine();
    s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
    if (s.Length == 0) return next();
    i = 0;
    return s[i++];
  }

  public string nextLine()
  {
    return Console.ReadLine();
  }

  public int nextInt()
  {
    return int.Parse(next());
  }

  public long nextLong()
  {
    return long.Parse(next());
  }

  public double nextDouble()
  {
    return double.Parse(next());
  }
}