#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}

int main() {
  int N;
  cin >> N;
  vector< pair< int, int > > g[200000];
  for(int i = 1; i < N; i++) {
    int x, y;
    cin >> x >> y;
    --x, --y;
    g[x].emplace_back(y, false);
    g[y].emplace_back(x, false);
  }
  vector< int > deg(N);
  for(int i = 1; i < N; i++) {
    int x, y;
    cin >> x >> y;
    --x, --y;
    deg[x] ^= 1;
    deg[y] ^= 1;
  }
  vector< int > ex(N);
  int add = 0;

  auto dfs = MFP([&](auto dfs, int idx, int par) -> bool {
    ex[idx] = deg[idx];
    for(auto &e : g[idx]) {
      if(e.first != par) {
        auto ret = dfs(e.first, idx);
        ex[idx] ^= ret;
        if(ret) {
          e.second = true;
          add += 1;
        }
      }
    }
    return ex[idx];
  });
  dfs(0, -1);

  auto dfs2 = MFP([&](auto dfs2, int idx, int par) -> pair< int, int > {
    int ret = 0;
    vector< int > add{0, 0};
    for(auto &e : g[idx]) {
      if(e.first != par) {
        auto res = dfs2(e.first, idx);
        if(e.second) add.emplace_back(res.second + 1);
        ret = max(ret, res.first);
      }
    }
    sort(add.rbegin(), add.rend());
    ret = max(ret, add[0] + add[1]);
    return {ret, add[0]};
  });


  add -= dfs2(0, -1).first;
  cout << add + (N - 1) << endl;
}