#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC push_options
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#include<bits/stdc++.h>
#include <xmmintrin.h>
#include <immintrin.h>
using namespace::std;
__attribute__((constructor))void init(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>
#include<ext/pb_ds/tag_and_trait.hpp>
// #include <boost/multiprecision/cpp_dec_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>
// namespace mp = boost::multiprecision;
// typedef mp::number<mp::cpp_dec_float<0>> cdouble;
// typedef mp::cpp_int cint;
template<typename T>using pbds=__gnu_pbds::tree<T,__gnu_pbds::null_type,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T>using pbds_map=__gnu_pbds::tree<T,T,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T,typename E>using hash_map=__gnu_pbds::gp_hash_table<T,E>;
template<typename T>using pqueue =__gnu_pbds::priority_queue<T, greater<T>,__gnu_pbds::rc_binomial_heap_tag>;
typedef long long lint;
#define INF (1LL<<60)
#define IINF (1<<30)
#define LINF (9223372036854775807LL)
#define EPS (1e-10)
#define endl ('\n')
//#define MOD 1000000007LL
#define MOD 998244353LL
//#define MOD 18446744069414584321ULL
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>inline void numout(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i<INF/2?i:"INF";f=1;}cout<<endl;}
template<typename T>inline void numout2(T t){for(auto i:t)numout(i);}
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)output(i);}
template<typename T>inline void _output(T t){bool f=0;for(lint i=0;i<t.size();i++){cout<<f?"":" "<<t[i];f=1;}cout<<endl;}
template<typename T>inline void _output2(T t){for(lint i=0;i<t.size();i++)output(t[i]);}
#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<int64_t> range(int64_t n){vector<int64_t>v(n);iota(v.begin(),v.end(),0LL);return v;}
inline vector<int64_t> range(int64_t a,int64_t b){vector<int64_t>v(b-a);iota(v.begin(),v.end(),a);return v;}
inline vector<int64_t> range(int64_t a,int64_t b,int64_t c){vector<int64_t>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;}
inline auto reversed(auto v){reverse(v.begin(),v.end());return v;}
#define all(n) begin(n),end(n)
#define dist(a,b,c,d) sqrt(pow(a-c,2)+pow(b-d,2))
//inline lint gcd(lint A,lint B){return B?gcd(B,A%B):A;}
//inline lint lcm(lint A,lint B){return A/gcd(A,B)*B;}
// inline cint cgcd(cint A,cint B){return B?cgcd(B,A%B):A;}
// inline cint clcm(cint A,cint B){return A/cgcd(A,B)*B;}
bool chmin(auto& s,const auto& t){bool res=s>t;s=min(s,t);return res;}
bool chmax(auto& s,const auto& t){bool res=s<t;s=max(s,t);return res;}
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)
auto call=[](auto f,auto... args){return f(f,args...);};
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...));}

template<typename T>
struct reroot{
    vector<vector<lint>>g;
    vector<lint>p_list;
    vector<T>p_table;
    vector<bool>p_checked;
    vector<map<lint,T>>table;
    vector<T>ans;
    reroot(auto g):g(g),p_list(g.size(),-1),p_checked(g.size(),0),table(g.size()){
        p_table.resize(g.size(),e);
        ans.resize(g.size(),e);
        dfs1(0,-1);
        for(int i=0;i<(int)g.size();++i)ans[i]=dfs2(i,-1);
    }
    T dfs1(lint n,lint p){
        p_list[n]=p;
        T tmp1=e,tmp2=e;
        vector<T>tmp(g[n].size());
        rep(i,g[n].size()){
            lint t=g[n][i];
            if(t==p)continue;
            table[n][t]=tmp1;
            tmp1=f(tmp1,tmp[i]=dfs1(t,n));
        }
        for(lint i=g[n].size()-1;i>=0;--i){
            lint t=g[n][i];
            if(t==p)continue;
            table[n][t]=f(table[n][t],tmp2);
            tmp2=f(tmp[i],tmp2);
        }
        return fix(table[n][p]=tmp1,n,p);
    }
    T dfs2(lint n,lint p){
        if(n==-1)return e;
        if(!p_checked[n]){
            p_checked[n]=1;
            p_table[n]=dfs2(p_list[n],n);
        }
        if(p==-1){
            return f(table[n][p_list[n]],p_table[n]);
        }else{
            if(p_list[n]==-1)return fix(table[n][p],n,p);
            else return fix(f(table[n][p],p_table[n]),n,p);
        }
    }
    vector<T>query(){
        return ans;
    }
    T e=make_tuple(0,map<int,int>(),-1);
    T f(T s,T t){
        for(auto e:get<1>(t)){
            if(e.second!=-1)get<1>(s)[e.first]=e.second;
        }
        return s;
    }
    T fix(T s,int n,int p){
        get<0>(s)=0;
        for(auto e:get<1>(s)){
            if(e.first==get<0>(s))get<0>(s)++;
            else break;
        }
        get<1>(s).clear();
        get<1>(s)[get<0>(s)]=n;
        get<2>(s)=n;
        return s;
    }
};

int main(){
    lint n,m;
    cin>>n>>m;
    vec a(m);
    rep(i,m)cin>>a[i];
    rep(i,m)a[i]--;
    mat g(n);
    rep(i,n-1){
        lint s,t;
        cin>>s>>t;
        s--;t--;
        g[s].push_back(t);
        g[t].push_back(s);
    }
    auto e=reroot<tuple<int,map<int,int>,int>>(g).query();
    vec mex(n);
    rep(i,n){
        mex[i]=0;
        for(auto d:get<1>(e[i])){
            if(d.first==mex[i])mex[i]++;
            else break;
        }
    }
    lint ans=0;
    rep(i,m){
        ans^=mex[a[i]];
    }
    if(ans==0){
        cout<<-1<<" "<<-1<<endl;
        return 0;
    }
    rep(i,m){
        if((ans^mex[a[i]])<mex[a[i]]){
            cout<<i+1<<" "<<get<1>(e[a[i]])[ans^mex[a[i]]]+1<<endl;
        }
    }

}