#line 2 "cpplib/util/template.hpp"
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx2")
#include<bits/stdc++.h>
using namespace std;
struct __INIT__{__INIT__(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}}__INIT__;
typedef long long lint;
#define INF (1LL<<60)
#define IINF (1<<30)
#define EPS (1e-10)
#define endl ('\n')
typedef vector<lint> vec;
typedef vector<vector<lint>> mat;
typedef vector<vector<vector<lint>>> mat3;
typedef vector<string> svec;
typedef vector<vector<string>> smat;
template<typename T>using V=vector<T>;
template<typename T>using VV=V<V<T>>;
template<typename T>inline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i;f=1;}cout<<endl;}
template<typename T>inline void output2(T t){for(auto i:t)output(i);}
template<typename T>inline void debug(T t){bool f=0;for(auto i:t){cerr<<(f?" ":"")<<i;f=1;}cerr<<endl;}
template<typename T>inline void debug2(T t){for(auto i:t)debug(i);}
#define loop(n) for(long long _=0;_<(long long)(n);++_)
#define _overload4(_1,_2,_3,_4,name,...) name
#define __rep(i,a) repi(i,0,a,1)
#define _rep(i,a,b) repi(i,a,b,1)
#define repi(i,a,b,c) for(long long i=(long long)(a);i<(long long)(b);i+=c)
#define rep(...) _overload4(__VA_ARGS__,repi,_rep,__rep)(__VA_ARGS__)
#define _overload3_rev(_1,_2,_3,name,...) name
#define _rep_rev(i,a) repi_rev(i,0,a)
#define repi_rev(i,a,b) for(long long i=(long long)(b)-1;i>=(long long)(a);--i)
#define rrep(...) _overload3_rev(__VA_ARGS__,repi_rev,_rep_rev)(__VA_ARGS__)

// #define rep(i,...) for(auto i:range(__VA_ARGS__)) 
// #define rrep(i,...) for(auto i:reversed(range(__VA_ARGS__)))
// #define repi(i,a,b) for(lint i=lint(a);i<(lint)(b);++i)
// #define rrepi(i,a,b) for(lint i=lint(b)-1;i>=lint(a);--i)
// #define irep(i) for(lint i=0;;++i)
// inline vector<long long> range(long long n){if(n<=0)return vector<long long>();vector<long long>v(n);iota(v.begin(),v.end(),0LL);return v;}
// inline vector<long long> range(long long a,long long b){if(b<=a)return vector<long long>();vector<long long>v(b-a);iota(v.begin(),v.end(),a);return v;}
// inline vector<long long> range(long long a,long long b,long long c){if((b-a+c-1)/c<=0)return vector<long long>();vector<long long>v((b-a+c-1)/c);for(int i=0;i<(int)v.size();++i)v[i]=i?v[i-1]+c:a;return v;}
// template<typename T>inline T reversed(T v){reverse(v.begin(),v.end());return v;}
#define all(n) begin(n),end(n)
template<typename T,typename E>bool chmin(T& s,const E& t){bool res=s>t;s=min<T>(s,t);return res;}
template<typename T,typename E>bool chmax(T& s,const E& t){bool res=s<t;s=max<T>(s,t);return res;}
const string ds="DRUL";
const vector<lint> dx={1,0,-1,0,1,1,-1,-1};
const vector<lint> dy={0,1,0,-1,1,-1,1,-1};
#define SUM(v) accumulate(all(v),0LL)
#if __cplusplus>=201703L
    template<typename T,typename ...Args>auto make_vector(T x,int arg,Args ...args){if constexpr(sizeof...(args)==0)return vector<T>(arg,x);else return vector(arg,make_vector<T>(x,args...));}
#endif
#define extrep(v,...) for(auto v:__MAKE_MAT__({__VA_ARGS__}))
#define bit(n,a) ((n>>a)&1)
vector<vector<long long>> __MAKE_MAT__(vector<long long> v){if(v.empty())return vector<vector<long long>>(1,vector<long long>());long long n=v.back();v.pop_back();vector<vector<long long>> ret;vector<vector<long long>> tmp=__MAKE_MAT__(v);for(auto e:tmp)for(long long i=0;i<n;++i){ret.push_back(e);ret.back().push_back(i);}return ret;}
using graph=vector<vector<int>>;
template<typename T>using graph_w=vector<vector<pair<int,T>>>;
template<typename T,typename E>ostream& operator<<(ostream& out,pair<T,E>v){out<<"("<<v.first<<","<<v.second<<")";return out;}
#if __cplusplus>=201703L
    constexpr inline long long powll(long long a,long long b){long long res=1;while(b--)res*=a;return res;}
#endif

template<typename T,typename E>pair<T,E>& operator+=(pair<T,E>&s,const pair<T,E>&t){s.first+=t.first;s.second+=t.second;return s;}
template<typename T,typename E>pair<T,E>& operator-=(pair<T,E>&s,const pair<T,E>&t){s.first-=t.first;s.second-=t.second;return s;}
template<typename T,typename E>pair<T,E> operator+(const pair<T,E>&s,const pair<T,E>&t){auto res=s;return res+=t;}
template<typename T,typename E>pair<T,E> operator-(const pair<T,E>&s,const pair<T,E>&t){auto res=s;return res-=t;}
// 128*1024*1024
#define BEGIN_STACK_EXTEND(size) void * stack_extend_memory_ = malloc(size);void * stack_extend_origin_memory_;char * stack_extend_dummy_memory_ = (char*)alloca((1+(int)(((long long)stack_extend_memory_)&127))*16);*stack_extend_dummy_memory_ = 0;asm volatile("mov %%rsp, %%rbx\nmov %%rax, %%rsp":"=b"(stack_extend_origin_memory_):"a"((char*)stack_extend_memory_+(size)-1024));
#define END_STACK_EXTEND asm volatile("mov %%rax, %%rsp"::"a"(stack_extend_origin_memory_));free(stack_extend_memory_);
#line 2 "main.cpp"

//copied by https://judge.yosupo.jp/submission/4713
using ll=long long;
vector<int> hungarian(const vector<vector<ll>>& a){
   int n=a.size(),p,q;
   vector<ll> fx(n,INF),fy(n,0);
   vector<int> x(n,-1),y(n,-1);
   rep(i,0,n)rep(j,0,n)chmax(fx[i],a[i][j]);
   for(int i=0;i<n;){
      vector<ll> t(n,-1),s(n+1,i);
      for(p=q=0;p<=q&&x[i]<0;p++){
         for(int k=s[p],j=0;j<n&&x[i]<0;j++){
            if(fx[k]+fy[j]==a[k][j]&&t[j]<0){
               s[++q]=y[j],t[j]=k;
               if(s[q]<0)for(p=j;p>=0;j=p){y[j]=k=t[j],p=x[k],x[k]=j;}
            }
         }
      }
      if(x[i]<0){
         ll d=INF;
         rep(k,0,q+1)rep(j,0,n)if(t[j]<0)chmin(d,fx[s[k]]+fy[j]-a[s[k]][j]);
         rep(j,0,n)fy[j]+=(t[j]<0?0:d);
         rep(k,0,q+1)fx[s[k]]-=d;
      } else i++;
   } return x;
}

int main(){
    lint k;
    cin>>k;
    vector<vector<int>> a(k);
    rep(i,k-1){
        lint s,t;
        cin>>s>>t;
        s--;t--;
        a[s].emplace_back(t);
        a[t].emplace_back(s);
    }
    lint n;
    cin>>n;
    vector<vector<int>> b(n);
    rep(i,n-1){
        lint s,t;
        cin>>s>>t;
        s--;t--;
        b[s].emplace_back(t);
        b[t].emplace_back(s);
    }
    auto dp=make_vector<int>(-2,k+1,k+1,n+1,n+1);
    vector<lint>p(n),sz(n,1);
    auto dfs2=[&](auto dfs2,lint now,lint pp)->void{
        p[now]=pp;
        for(auto e:b[now]){
            if(e==pp)continue;
            dfs2(dfs2,e,now);
            sz[now]+=sz[e];
        }
    };
    dfs2(dfs2,0,-1);
    // auto size=[&](int bnow,int bp){
    //     if(bp==-1)return n;
    //     return p[bnow]==bp?sz[bnow]:n-sz[bp];
    // };
    auto dfs=[&](auto dfs,lint anow,lint ap,lint bnow,lint bp)->lint{
        lint res2=-1;
        if(dp[anow][ap!=-1?ap:k][bnow][bp!=-1?bp:n]!=-2){
            return dp[anow][ap!=-1?ap:k][bnow][bp!=-1?bp:n];
        }
        const int asz=(int)a[anow].size()-(ap!=-1);
        const int bsz=(int)b[bnow].size()-(bp!=-1);
        // if(asz>bsz)return dp[anow][ap!=-1?ap:k][bnow][bp!=-1?bp:n]=-1;

        if(ap!=-1&&bp!=-1){
            // int sz=size(bnow,bp)-1;
            int bcnt=0;
            for(auto bto:b[bnow]){
                if(bp==bto)continue;
                auto res=dfs(dfs,anow,ap,bto,bnow);
                if(res==-1){
                    bcnt++;
                    continue;
                }
                chmax(res2,res+1);
                bcnt++;
            }
        }
        vector<vector<ll>>v(bsz,vector<ll>(bsz));
        int acnt=0;
        // rep(i,asz)mf.add_edge(asz+bsz,i,1,0);
        // rep(i,bsz)mf.add_edge(i+asz,asz+bsz+1,1,0);
        // {
        //     int bcnt=0;
        //     for(auto bto:b[bnow]){
        //         if(bp==bto)continue;
        //         // cerr<<bto<<" "<<bnow<<endl;
        //         mf.add_edge(asz+bsz,bcnt+asz,1,-size(bto,bnow));
        //         bcnt++;
        //     }
        // }
        if(asz<=bsz){
            for(auto ato:a[anow]){
                if(ap==ato)continue;
                int bcnt=0;
                for(auto bto:b[bnow]){
                    if(bp==bto)continue;
                    auto res=dfs(dfs,ato,anow,bto,bnow);
                    if(res!=-1)v[acnt][bcnt]=res;
                    else v[acnt][bcnt]=-IINF;
                    bcnt++;
                }
                // assert(bsz==bcnt);
                acnt++;
            }
            // assert(asz==acnt);
            auto res=hungarian(v);
            bool ok=1;
            lint cost=0;
            rep(i,asz){
                if(v[i][res[i]]!=-IINF)cost+=v[i][res[i]];
                else{
                    ok=0;
                    break;
                }
            }
            if(ok)chmax(res2,cost);
        }
        return dp[anow][ap!=-1?ap:k][bnow][bp!=-1?bp:n]=res2;
    };
    lint ans=-1;
    rep(i,k)rep(j,n){
        auto res=dfs(dfs,i,-1,j,-1);
        if(res==-1)continue;
        chmax(ans,res);
    }
    cerr<<ans<<endl;
    if(ans==-1)cout<<-1<<endl;
    else cout<<k-1+ans<<endl;
}