#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; (i) < (int)(n); ++ (i))
using namespace std;
template <class T, class U> inline void chmin(T & a, U const & b) { a = min<T>(a, b); }

int solve(int n, const vector<vector<int> > & g, const vector<vector<int> > & h) {
    const int INF = n;
    function<pair<array<int, 3>, int> (int, int)> go = [&](int x, int parent) {
        array<int, 3> dp = { INF, INF, INF };
        int odd = (h[x].size() % 2);
        dp[0] = 0;
        dp[odd] = 0;
        for (int y : g[x]) if (y != parent) {
            auto [dp1, odd1] = go(y, x);
            array<int, 3> dp2 = { INF, INF, INF };
            REP (i, 3) REP (j, 3 - i) {
                chmin(dp2[i + j], dp[i] + dp1[j] + (odd1 - j + 2) % 2);
            }
            dp = dp2;
            odd += odd1;
        }
        return make_pair(dp, odd);
    };
    return (n - 1) + go(0, -1).first[2];
}

int main() {
    int n; cin >> n;
    vector<vector<int> > g(n);
    REP (i, n - 1) {
        int a, b; cin >> a >> b;
        -- a;
        -- b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    vector<vector<int> > h(n);
    REP (i, n - 1) {
        int c, d; cin >> c >> d;
        -- c;
        -- d;
        h[c].push_back(c);
        h[d].push_back(d);
    }
    cout << solve(n, g, h) << endl;
    return 0;
}