//Let's join Kaede Takagaki Fan Club !!
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cassert>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <functional>
#include <iostream>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <cassert>
#include <iomanip>
#include <chrono>
#include <random>
#include <bitset>
#include <complex>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
#define int long long
//#define L __int128
typedef long long ll;
typedef pair<int,int> P;
typedef pair<int,P> P1;
typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define a first
#define b second
#define fi first
#define sc second
#define rng(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,x) for(int i=0;i<x;i++)
#define repn(i,x) for(int i=1;i<=x;i++)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())
#define all(x) x.begin(),x.end()
#define si(x) int(x.size())
 
#ifdef LOCAL
#define dmp(x) cerr<<__LINE__<<" "<<#x<<" "<<x<<endl
#else
#define dmp(x) void(0)
#endif
 
template<class t,class u> bool chmax(t&a,u b){if(a<b){a=b;return true;}else return false;}
template<class t,class u> bool chmin(t&a,u b){if(b<a){a=b;return true;}else return false;}
 
template<class t> using vc=vector<t>;
 
template<class t,class u>
ostream& operator<<(ostream& os,const pair<t,u>& p){
	return os<<"{"<<p.fi<<","<<p.sc<<"}";
}
 
template<class t> ostream& operator<<(ostream& os,const vc<t>& v){
	os<<"{";
	for(auto e:v)os<<e<<",";
	return os<<"}";
}
 
 //https://codeforces.com/blog/entry/62393
struct custom_hash {
	static uint64_t splitmix64(uint64_t x) {
		// http://xorshift.di.unimi.it/splitmix64.c
		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}
 
	size_t operator()(uint64_t x) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
	
	size_t operator()(pair<int,int> x)const{
		return operator()(uint64_t(x.first)<<32|x.second);
	}
};
//unordered_set -> dtype, null_type
//unordered_map -> dtype(key), dtype(value)
using namespace __gnu_pbds;
template<class t,class u>
using hash_table=gp_hash_table<t,u,custom_hash>;

template<class T>
void g(T &a){
	cin >> a;
}
template<class T>
void o(const T &a,bool space=false){
	cout << a << (space?' ':'\n');
}
//ios::sync_with_stdio(false);
const ll mod = 998244353;
//const ll mod = 1000000007;
mt19937_64 mt(chrono::steady_clock::now().time_since_epoch().count());
template<class T>
void add(T&a,T b){
	a+=b;
	if(a >= mod) a-=mod;
}
ll modpow(ll x,ll n){
	ll res=1;
	while(n>0){
		if(n&1) res=res*x%mod;
		x=x*x%mod;
		n>>=1;
	}
	return res;
}
#define _sz 1
ll F[_sz],R[_sz];
void make(){
	F[0] = 1;
	for(int i=1;i<_sz;i++) F[i] = F[i-1]*i%mod;
	R[_sz-1] = modpow(F[_sz-1], mod-2);
	for(int i=_sz-2;i>=0;i--) R[i] = R[i+1] * (i+1) % mod;
}
ll C(int a,int b){
	if(b < 0 || a < b) return 0;
	return F[a]*R[b]%mod*R[a-b]%mod;
}
int dp[105][105][105];
int n, m;
vc<int>sm[105], bg[105];
int cntsm[105], cntbg[105];
void dfssm(int v, int u){ cntsm[v] = 1; for(auto a:sm[v]) if(a != u){
	dfssm(a, v); cntsm[v] += cntsm[a]; } }
void dfsbg(int v, int u){ cntbg[v] = 1; for(auto a:bg[v]) if(a != u){
	dfsbg(a, v); cntbg[v] += cntbg[a]; } }
template< typename flow_t, typename cost_t >
struct PrimalDual {
	const cost_t inf;
	struct edge{
		int to;
		flow_t cap;
		cost_t cost;
		int rev;
		bool isrev;
	};
	vc<vc<edge>>g;
	vc<cost_t>pot, dist;
	vc<int>prevv, preve;
	
	PrimalDual(int n): g(n), inf(numeric_limits<cost_t>::max()) {}
	
	void add_edge(int from, int to, flow_t cap, cost_t cost){
		g[from].emplace_back((edge) {to, cap, cost, (int) g[to].size(), false});
		g[to].emplace_back((edge) {from, 0, -cost, (int) g[from].size()-1, true});
	}
	
	cost_t mcf(int s, int t, flow_t f){
		int n = (int)g.size();
		cost_t ret = 0;
		using pi = pair<cost_t, int>;
		priority_queue<pi, vc<pi>, greater<pi>>que;
		
		pot.assign(n, 0);
		preve.assign(n, -1);
		prevv.assign(n, -1);
		
		bool fs = true;
		while(f > 0){
			dist.assign(n, inf);
			
			que.emplace(0, s);
			dist[s] = 0;
			
			while(!que.empty()){
				pi p = que.top(); que.pop();
				if(dist[p.sc] < p.fi) continue;
				
				rep(i, g[p.sc].size()){
					edge &e = g[p.sc][i];
					cost_t nc = dist[p.sc] + e.cost + pot[p.sc] - pot[e.to];
					
					if(e.cap > 0 && dist[e.to] > nc){
						dist[e.to] = nc;
						prevv[e.to] = p.sc, preve[e.to] = i;
						que.emplace(dist[e.to], e.to);
					}
				}
			}
			
			if(dist[t] == inf){
				//can not send f units flow
				return -1;
			}
			rep(v, n) pot[v] += dist[v];
			flow_t addflow = f;
			for(int v=t;v!=s;v=prevv[v]) chmin(addflow, g[prevv[v]][preve[v]].cap);
			
			f -= addflow;
			ret += addflow * pot[t];
			
			for(int v=t;v!=s;v=prevv[v]){
				edge &e = g[prevv[v]][preve[v]];
				e.cap -= addflow;
				g[v][e.rev].cap += addflow;
			}
		}
		return ret;
	}
	void output(){
		rep(i, g.size()){
			for(auto &e:g[i]){
				if(e.isrev) continue;
				auto &rev_e = g[e.to][e.rev];
				cout << i << "->" << e.to << "(flow:" << rev_e.cap << "/" << rev_e.cap + e.cap << ")" << endl;
			}
		}
	}
};
void solve(){
	cin>>n;
	rep(i,n-1){
		int a,b;cin>>a>>b;
		sm[a].pb(b);
		sm[b].pb(a);
	}
	cin>>m;
	rep(i,m-1){
		int a,b;cin>>a>>b;
		bg[a].pb(b);
		bg[b].pb(a);
	}
	dfssm(1, -1);
	dfsbg(1, -1);
	vc<int>smv; repn(i, n) smv.pb(i);
	vc<P>bgv; repn(i, m) for(auto a:bg[i]) bgv.eb(i, a);
	sort(all(smv), [](int a, int b){
		return cntsm[a] < cntsm[b];
	});
	sort(all(bgv), [](P a, P b){
		int eva = (cntbg[a.a] > cntbg[a.b]?cntbg[a.b]:m-cntbg[a.a]);
		int evb = (cntbg[b.a] > cntbg[b.b]?cntbg[b.b]:m-cntbg[b.a]);
		return eva < evb;
	});
	rep(i, 105) rep(j, 105) rep(k, 105) dp[i][j][k] = -INF;
	
	for(auto s:smv){
		for(auto b:bgv){
			int u = b.a, v = b.b;
			//calc dp[s][u][v]
			int eva = (cntbg[u] > cntbg[v]?cntbg[v]:m-cntbg[u]);
			for(auto ch:bg[v]){
				//v, ch
				if(ch == u) continue;
				int evb = (cntbg[v] > cntbg[ch]?cntbg[ch]:m-cntbg[v]);
				if(eva < evb) continue;
				chmax(dp[s][u][v], dp[s][v][ch] + 1);
			}
			vc<int>le, ri;
			for(auto ch:sm[s]) if(cntsm[ch] < cntsm[s]) le.pb(ch);
			for(auto ch:bg[v]) {
				if(ch == u) continue;
				int evb = (cntbg[v] > cntbg[ch]?cntbg[ch]:m-cntbg[v]);
				if(eva < evb) continue;
				ri.pb(ch);
			}
			
			if(le.size() > ri.size()) continue;
			PrimalDual<int, int>pd(le.size()+ri.size()+5);
			int ss = le.size()+ri.size()+3;
			int t = ss+1;
			
			rep(i, le.size()){
				rep(j, ri.size()){
					if(dp[le[i]][v][ri[j]] < 0) continue;
					pd.add_edge(i, j+le.size(), 1, 1000 - dp[le[i]][v][ri[j]]);
				}
			}
			
			rep(i, le.size()) pd.add_edge(ss, i, 1, 0);
			rep(i, ri.size()) pd.add_edge(i+le.size(), t, 1, 0);
			
			auto ret = pd.mcf(ss, t, le.size());
			if(ret < 0) continue;
			chmax(dp[s][u][v], (int)le.size() * 1000 - ret + (int)le.size());
		}
	}
	int ans = -INF;
	repn(v, m){
		int tmp = -INF;
		vc<int>le, ri;
		for(auto ch:sm[1]) le.pb(ch);
		for(auto ch:bg[v]) ri.pb(ch);
		if(le.size() > ri.size()) continue;
		PrimalDual<int, int>pd(le.size()+ri.size()+5);
		int s = le.size()+ri.size()+3;
		int t = s+1;
		
		rep(i, le.size()){
			rep(j, ri.size()){
				if(dp[le[i]][v][ri[j]] < 0) continue;
				pd.add_edge(i, j+le.size(), 1, 1000 - dp[le[i]][v][ri[j]]);
			}
		}
		
		rep(i, le.size()) pd.add_edge(s, i, 1, 0);
		rep(i, ri.size()) pd.add_edge(i+le.size(), t, 1, 0);
		
		auto ret = pd.mcf(s, t, le.size());
		if(ret < 0) continue;
		tmp = (int)le.size() * 1000 - ret + (int)le.size();
		chmax(ans, tmp);
	}
	if(ans < 0) ans = -1;
	o(ans);
}
signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	int t; t = 1; //cin >> t;
	while(t--) solve();
}