#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
vector<vector<int>>to(200005);
bool deg[200005], sum[200005];
int dp[200000][3];
void predfs(int idx, int p = -1) {
	sum[idx] = deg[idx];
	for (auto &nv : to[idx]) {
		if (p == nv)continue;
		predfs(nv, idx);
		sum[idx] ^= sum[nv];
	}
}
void dfs(int v, int p = -1) {
	vector<int>sub(3, 0);
	for (auto nv : to[v]) {
		if (p == nv)continue;
		dfs(nv, v);
		vector<int>subsub(3, INF);
		rep(i, 3)rep(j, 3) {
			if (i + j >= 3)continue;
			chmin(subsub[i+j],sub[i] + dp[nv][j] + (j + sum[nv]) % 2);
		}
		swap(sub, subsub);
	}
	rep(i, 3) dp[v][i] = sub[i];
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n; cin >> n;
	rep(i, n - 1) {
		int a, b; cin >> a >> b;
		a--, b--;
		to[a].push_back(b);
		to[b].push_back(a);
	}
	rep(i, n - 1) {
		int a, b; cin >> a >> b;
		a--, b--;
		deg[a] ^= 1;
		deg[b] ^= 1;
	}
	predfs(0);
	dfs(0);
	cout << min(dp[0][0], dp[0][2]) + n - 1 << endl;
	return 0;
}