/**
 *  author: ivanzuki   
 *  created: Wed May 12 2021
**/
#include <bits/stdc++.h>

using namespace std;

const int inf = (int) 1e9;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<vector<int>> g(n);
  for (int i = 0; i < n - 1; i++) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  vector<int> deg(n);
  for (int i = 0; i < n - 1; i++) {
    int x, y;
    cin >> x >> y;
    --x; --y;
    ++deg[x];
    ++deg[y];
  }
  vector<vector<vector<int>>> dp(n, vector<vector<int>>(4, vector<int>(2, inf)));
  function<void(int, int)> DFS = [&](int v, int pv) {
    dp[v][deg[v] % 2][deg[v] % 2] = 0;
    for (int u : g[v]) {
      if (u == pv) {
        continue;
      }
      DFS(u, v);
      // (# of odd-degree vertices, is v an odd-degree vertex?)
      vector<vector<int>> new_dp(4, vector<int>(2, inf));
      // add the (v, u) edge
      for (int x = 0; x <= 3; x++) {
        for (int y = 0; y < 2; y++) {
          for (int z = 0; z <= 3; z++) {
            for (int w = 0; w < 2; w++) {
              {
                // add the edge
                int p = x + (y == 1 ? -1 : 1) + z + (w == 1 ? -1 : 1);
                int q = 1 - y;
                if ((p >= 0 && p <= 2) || (p == 3 && q == 1)) {
                  new_dp[p][q] = min(new_dp[p][q], 1 + dp[v][x][y] + dp[u][z][w]);
                }
              }
              {
                // do not add the edge
                int p = x + z;
                int q = y;
                if ((p >= 0 && p <= 2) || (p == 3 && q == 1)) {
                  new_dp[p][q] = min(new_dp[p][q], dp[v][x][y] + dp[u][z][w]);
                }
              }
            }
          }
        }
      }
      dp[v] = new_dp;
      // new_dp[0][0] = min(new_dp[0][0], 1 + dp[v][1][1] + dp[u][1][1]);
      // new_dp[1][0] = min(new_dp[1][0], 1 + dp[v][1][1] + dp[u][0][0]);
      // new_dp[1][1] = min(new_dp[1][1], 1 + dp[v][0][0] + dp[u][1][1]);
      // new_dp[2][0] = min(new_dp[2][0], 1 + dp[v][3][1] + dp[u][1][1]);
      // new_dp[2][0] = min(new_dp[2][0], 1 + dp[v][1][1] + dp[u][1][0]);
      // new_dp[2][0] = min(new_dp[2][0], 1 + dp[v][1][1] + dp[u][3][1]);
      // new_dp[2][1] = min(new_dp[2][1], 1 + dp[v][1][0] + dp[u][3][1]);
      // new_dp[2][1] = min(new_dp[2][1], 1 + dp[v][0][0] + dp[u][0][0]);
      // new_dp[2][1] = min(new_dp[2][1], 1 + dp[v][0][0] + dp[u][3][1]);
      // new_dp[2][1] = min(new_dp[2][1], 1 + dp[v][1][0] + dp[u][0][0]);
      // new_dp[3][1] = min(new_dp[3][1], 1 + dp[v][2][0] + dp[u][1][1]);
      // new_dp[3][1] = min(new_dp[3][1], 1 + dp[v][1][0] + dp[u][0][0]);
      // new_dp[3][1] = min(new_dp[3][1], 1 + dp[v][1][0] + dp[u][2][1]);
      // new_dp[3][1] = min(new_dp[3][1], 1 + dp[v][0][0] + dp[u][3][1]);
      // new_dp[3][1] = min(new_dp[3][1], 1 + dp[v][0][0] + dp[u][1][0]);
      // do not add the (v, u) edge
      // new_dp[0][0] = min(new_dp[0][0], 
    }
  };
  DFS(0, -1);
  int ans = n - 1 + min({dp[0][0][0], dp[0][2][0], dp[0][2][1]});
  cout << ans << '\n';
  return 0;
}