#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
int n;
vector<P> g[200020];
int deg[200020];
int ans;
void dfs(int x, int p){
	for(auto &q:g[x]){
		int y=q.first;
		if(y==p) continue;
		dfs(y, x);
		if(deg[y]){
			deg[y]^=1;
			deg[x]^=1;
			q.second=1;
			ans++;
		}else{
			q.second=-1;
		}
	}
}
void dfs0(int x, int p, int t){
	for(auto &q:g[x]){
		int y=q.first;
		if(y==p){
			q.second=t;
			continue;
		}
		dfs0(y, x, q.second);
	}
}
int r;
int d[200020];
void dfs2(int x, int p){
	for(auto q:g[x]){
		int y=q.first;
		if(y==p) continue;
		d[y]=d[x]+q.second;
		if(d[y]>d[r]) r=y;
		dfs2(y, x);
	}
}
void dfs3(int x, int p){
	for(auto q:g[x]){
		int y=q.first;
		if(y==p) continue;
		d[y]=d[x]+q.second;
		dfs3(y, x);
	}
}
int main()
{
	cin>>n;
    for(int i=0; i<n-1; i++){
        int a, b;
        cin>>a>>b;
        a--; b--;
        g[a].push_back({b, 0});
        g[b].push_back({a, 0});
    }
    for(int i=0; i<n-1; i++){
        int c, d;
        cin>>c>>d;
        c--; d--;
        deg[c]^=1;
		deg[d]^=1;
    }
	dfs(0, -1);
	dfs0(0, -1, -1);
	dfs2(0, -1);
	d[r]=0;
	dfs3(r, -1);
	int mx=0;
	for(int i=0; i<n; i++) mx=max(mx, d[i]);
	ans-=mx;
	ans+=n-1;
	cout<<ans<<endl;
    return 0;
}