#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

template<typename T>
vector<vector<T>> vec2d(int n, int m, T v){
    return vector<vector<T>>(n, vector<T>(m, v));
}

template<typename T>
vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){
    return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v)));
}

template<typename T>
void print_vector(vector<T> v, char delimiter=' '){
    if(v.empty()) {
        cout << endl;
        return;
    }
    for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter;
    cout << v.back() << endl;
}

const ll inf = 1e18;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n; cin >> n;
    vector<vector<int>> g_red(n), g_black(n);
    for(int i = 0; i < n-1; i++){
        int a, b; cin >> a >> b; a--; b--;
        g_red[a].push_back(b);
        g_red[b].push_back(a);
    }
    for(int i = 0; i < n-1; i++){
        int a, b; cin >> a >> b; a--; b--;
        g_black[a].push_back(b);
        g_black[b].push_back(a);
    }
    auto dp = vec3d(n, 2, 3, inf);
    function<void(int, int)> dfs = [&](int v, int par){
        if(g_black[v].size()%2 == 1){
            dp[v][1][0] = 0;
            dp[v][0][1] = 0;
        }else{
            dp[v][0][0] = 0;
        }
        for(int to: g_red[v]){
            if(to == par) continue;
            dfs(to, v);
            auto nx = vec2d(2, 3, inf);
            for(int i = 0; i < 2; i++){
                for(int j = 0; j < 3; j++){
                    for(int ii = 0; ii < 2; ii++){
                        for(int jj = 0; jj < 3; jj++){
                            if(j+jj > 2) continue;
                            chmin(nx[i^ii][j+jj], dp[v][i][j]+dp[to][ii][jj]+ii);
                        }
                    }
                }
            }
            dp[v] = nx;
        }
    };
    dfs(0, -1);
    cout << dp[0][0][2]+(n-1) << endl;
}