#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;

int N;
vector<int> G[200000];
int deg[200000];
int dp[200000][3];

void calc(int v, int p){
    for(auto to : G[v]){
        if(to == p) continue;
        calc(to, v);
        deg[v] += deg[to];
        int nxt[3] = {INF, INF, INF};
        for(int i = 0; i < 3; i++){
            for(int j = 0; i + j < 3; j++){
                nxt[i + j] = min(nxt[i + j], dp[v][i] + dp[to][j] + !(deg[to] % 2 == j % 2));
            }
        }
        swap(dp[v], nxt);
    }
}

struct UF{
    vector<int> par, sz;
    UF(){}
    UF(int n):par(n), sz(n, 1){
        iota(par.begin(), par.end(), 0);
    }
    int find(int x){
        if(x == par[x]) return x;
        return par[x] = find(par[x]);
    }
    void unite(int x, int y){
        x = find(x); y = find(y);
        if(x == y) return;
        if(sz[x] < sz[y]) swap(x, y);
        sz[x] += sz[y];
        par[y] = x;
    }
    bool same(int x, int y){
        return find(x) == find(y);
    }
};

int main(){
    cin >> N;
    assert(2 <= N && N <= 200000);
    UF ufr(N), ufb(N);
    for(int i = 0; i < N - 1; i++){
        int A, B;
        cin >> A >> B;
        A--; B--;
        G[A].push_back(B);
        G[B].push_back(A);
        ufr.unite(A, B);
    }
    assert(ufr.sz[ufr.find(0)] == N);
    for(int i = 0; i < N - 1; i++){
        int C, D;
        cin >> C >> D;
        C--; D--;
        deg[C]++;
        deg[D]++;
        ufb.unite(C, D);
    }
    assert(ufb.sz[ufb.find(0)] == N);
    calc(0, -1);
    cout << min(dp[0][0], dp[0][2]) + N - 1 << endl;
}