#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 6 "cpplib/graph_tree/push_relabel.hpp"

/**
 * @brief 最大流(push_relabel法O(V^2√E))
 */
template<typename T>
class push_relabel{
    int n;
    T f=0;
    using i64=long long;
    struct edge{
        int from,to,rev;
        T flow,cap;
    };
    std::vector<i64>h,d;
    std::vector<std::vector<edge*>>g;
    std::vector<size_t>seen;
    std::priority_queue<std::pair<i64,int>,std::vector<std::pair<i64,int>>,std::greater<std::pair<i64,int>>>que;
    public:
    push_relabel(int n):n(n){
        h.resize(n,0);
        d.resize(n,0);
        g.resize(n);
        seen.resize(n,0);
    }
    void add_edge(int u,int v,T cap){
        g[u].emplace_back(new edge{u,v,(int)g[v].size(),0,cap});
        g[v].emplace_back(new edge{v,u,(int)g[u].size()-1,0,0});
    }
    void push(edge* e){
        int u=e->from,v=e->to;
        i64 df=std::min<i64>(d[u],e->cap-e->flow);
        e->flow+=df;
        g[v][e->rev]->flow-=df;
        d[u]-=df;
        d[v]+=df;
        if(d[v]>0)que.emplace(h[v],v);
        if(d[u]>0)que.emplace(h[u],u);
    }
    void relabel(int u){
        i64 mn=n*2;
        for(edge* e:g[u]){
            if(e->cap-e->flow>0){
                mn=std::min(mn,h[e->to]);
            }
        }
        h[u]=1+mn;
        que.emplace(h[u],u);
    }
    void discharge(int u){
        while(d[u]>0){
            if(seen[u]<g[u].size()){
                edge* e=g[u][seen[u]];
                if(e->cap-e->flow>0 && h[u]==h[e->to]+1){
                    push(e);
                }else{
                    seen[u]+=1;
                }
            }else{
                relabel(u);
                seen[u]=0;
            }
        }
    }
    T run(int s,int t){
        h[s]=n;
        for(auto e:g[s]){
            d[s]+=e->cap;
            push(e);
        }
        while(!que.empty()){
            int u=que.top().second;
            que.pop();
            if(u==s||u==t)continue;
            discharge(u);
        }
        for(auto e:g[s])f+=e->flow;
        return f;
    }
};
#line 6 "cpplib/graph_tree/min_cost_flow.hpp"

/**
 * @brief 最小費用流(CostScaling)
 */

//Resは答えがlong longの最大値を超える時用
template<typename T,typename Res=T>
struct min_cost_flow{
    int v;
    Res ans=0;
    struct edge{
        int to;
        T cap,cost,st;
        int rev;
        bool is_rev,edge_rev;
        int id;
    };
    push_relabel<T> mf;
    std::vector<T>p;
    std::vector<vector<edge*>>e;//辺のキャパシティ
    std::vector<T>d;//頂点のキャパシティ
    std::queue<int>active;
    std::vector<tuple<int,int,T,T,T>>edges;
    T eps=1;
    int idx=0;
    std::vector<T>res;
    min_cost_flow(int v):v(v),mf(v+2),p(v,0),e(v),d(v,0){}
    void add_edge(int from,int to,T mn,T mx,T cost){
        edges.emplace_back(from,to,mn,mx,cost);
        res.push_back(0);
        if(from==to){
            if(cost<0)res[idx++]=mx,ans+=mx*cost;
            else res[idx++]=mn,ans+=mn*cost;
            return;
        }
        if(cost>=0){
            e[from].push_back(new edge{to,mx-mn,cost*v,mn,(int)e[to].size(),0,0,idx});
            e[to].push_back(new edge{from,0,-cost*v,mn,(int)e[from].size()-1,1,0,idx++});
            ans+=mn*cost;
            d[from]-=mn;d[to]+=mn;
            eps=max(eps,cost*v*v);
            mf.add_edge(from,to,mx-mn);
        }
        else{
            e[to].push_back(new edge{from,mx-mn,-cost*v,mx,(int)e[from].size(),0,1,idx});
            e[from].push_back(new edge{to,0,cost*v,mx,(int)e[to].size()-1,1,1,idx++});
            ans+=mx*cost;
            d[from]-=mx;d[to]+=mx;
            eps=max(eps,-cost*v*v);
            mf.add_edge(to,from,mx-mn);
        }
    }
    void add_edge(int from,int to,T cap,T cost){
        add_edge(from,to,T(),cap,cost);
    }

    Res flow(){
        for(;eps;eps>>=1){
            for(int i=0;i<v;i++){
                for(auto ed:e[i]){
                    if(ed->is_rev)continue;
                    if(ed->cost-p[i]+p[ed->to]<0){
                        T f=ed->cap;
                        ed->cap-=f;
                        d[i]-=f;
                        d[ed->to]+=f;
                        e[ed->to][ed->rev]->cap+=f;
                    }
                    if(ed->cost-p[i]+p[ed->to]>0){
                        T f=-e[ed->to][ed->rev]->cap;
                        ed->cap-=f;
                        d[i]-=f;
                        d[ed->to]+=f;
                        e[ed->to][ed->rev]->cap+=f;
                    }
                }
            }
            for(int i=0;i<v;i++)if(d[i]>0){active.emplace(i);}
            while(!active.empty()){
                int node=active.front();
                active.pop();
                if(d[node]<=0)continue;
                bool b=0;
                for(auto ed:e[node]){
                    if(!d[node])break;
                    if(-eps<=ed->cost-p[node]+p[ed->to]&&ed->cost-p[node]+p[ed->to]<0){
                        auto f=std::min(d[node],ed->cap);
                        if(!f)continue;
                        ed->cap-=f;
                        d[node]-=f;
                        d[ed->to]+=f;
                        e[ed->to][ed->rev]->cap+=f;
                        if(d[ed->to]>0)active.emplace(ed->to);
                        b=1;
                    }
                }
                if(d[node]>0)active.emplace(node);
                if(!b)p[node]+=eps;
            }
        }
        for(int i=0;i<v;i++)for(auto ed:e[i]){
            if(ed->is_rev)continue;
            ans+=e[ed->to][ed->rev]->cap*(ed->cost/v);
        }
        return ans;
    }
    Res run(int s,int t,T f=-1,bool check=0){
        d[s]+=f;
        d[t]-=f;
        if(check){
            // debug(d);
            int cnt=0;
            for(int i=0;i<v;++i){
                if(d[i]>0){
                    mf.add_edge(v,i,d[i]);
                    cnt+=d[i];
                }else if(d[i]<0){
                    mf.add_edge(i,v+1,-d[i]);
                }
            }
            lint t=mf.run(v,v+1);
            if(t<cnt){
                return IINF;
            }
        }
        return flow();
    }
    Res run(std::vector<T>b){
        for(int i=0;i<v;++i)d[i]+=b[i];
        return flow();
    }
    std::vector<T> flow_result(){
        for(int i=0;i<v;i++)for(auto ed:e[i]){
            if(ed->is_rev)continue;
            res[ed->id]=ed->st+e[ed->to][ed->rev]->cap*(ed->edge_rev?-1:1);
        }
        return res;
    }
    //flow_resultを渡す
    std::vector<T>potential(const std::vector<T>& f){
        std::vector<T>p(v,0);
        std::vector<tuple<int,int,T>>g;
        int idx=0;
        for(auto [from,to,mn,mx,cost]:edges){
            if(mn<f[idx])g.emplace_back(to,from,-cost);
            if(f[idx]<mx)g.emplace_back(from,to,cost);
            idx++;
        }
        for(int i=0;i<v;++i)for(auto [s,t,c]:g){
            p[t]=std::min(p[t],p[s]+c);
        }
        return p;
    }
};
#line 3 "main.cpp"

int main(){
    lint k;
    cin>>k;
    mat 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;
    mat 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<lint>(-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){
            // 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++;
            }
        }
        min_cost_flow<int>mf(asz+bsz+2);
        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++;
        //     }
        // }
        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)mf.add_edge(acnt,asz+bcnt,1,-res);
                bcnt++;
            }
            // assert(bsz==bcnt);
            acnt++;
        }
        // assert(asz==acnt);
        auto cost=mf.run(asz+bsz,asz+bsz+1,asz,1);
        if(cost!=IINF)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);
    }
    if(ans==-1)cout<<-1<<endl;
    else cout<<k-1+ans<<endl;
}