#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
///// This part below is only for debug, not used /////
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;
///// END /////
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/tag_and_trait.hpp>
using namespace __gnu_pbds; // find_by_order(), order_of_key()
template<typename TK> using pbds_set = tree<TK, null_type, less<TK>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename TK, typename TV> using pbds_map = tree<TK, TV, less<TK>, rb_tree_tag, tree_order_statistics_node_update>;
*/

vector<vector<int>> red, black;
struct Info
{
    int x0, x1, x2, v;
    Info (int x0=0, int x1=0, int x2=0, int v=0): x0(x0), x1(x1), x2(x2), v(v) {}
};

constexpr int INF = 1e9;
Info dfs(int now, int prv)
{
    int v = black[now].size() % 2;

    Info ret(0, INF, INF, v);

    vector<int> x0s, x1s, x2s;
    if (v) x0s.emplace_back(0), x1s.emplace_back(0), x2s.emplace_back(INF);

    for (auto nxt : red[now]) if (nxt != prv)
    {
        Info i = dfs(nxt, now);
        x0s.emplace_back(i.x0);
        x1s.emplace_back(i.x1);
        x2s.emplace_back(i.x2);
        ret.v += i.v;
    }

    ret.x0 = accumulate(ALL(x0s), 0);

    REP(i, x2s.size()) mmin(ret.x2, ret.x0 + x2s[i] - x0s[i]);
    REP(i, x1s.size()) mmin(ret.x1, ret.x0 + x1s[i] - x0s[i]);

    REP(i, x1s.size()) x1s[i] -= x0s[i];

    sort(ALL(x1s));
    if (x1s.size() > 1) mmin(ret.x2, ret.x0 + x1s[0] + x1s[1]);

    if (ret.v % 2)
    {
        ret.x0++;
        ret.x2++;
    }
    else
    {
        ret.x1++;
    }
    return ret;
}

int main()
{
    int N;
    cin >> N;

    red.resize(N);
    black.resize(N);
    REP(_, N - 1)
    {
        int a, b;
        cin >> a >> b;
        a--, b--;
        red[a].push_back(b);
        red[b].push_back(a);
    }
    REP(_, N - 1)
    {
        int c, d;
        cin >> c >> d;
        c--, d--;
        black[c].push_back(d);
        black[d].push_back(c);
    }

    Info info = dfs(0, -1);
    dbg(info.x0);
    dbg(info.x1);
    dbg(info.x2);
    dbg(info.v);
    cout << min(info.x0, info.x2) + N - 1 << endl;
}