#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define Per(i,sta,n) for(int i=n-1;i>=sta;i--)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};

int n,m;
int a[200010];
vector<int> G[200010];
int dp[200010],dp2[200010];
int p[200010];
int cnt[200010][25],cnt2[200010][25];

void dfs1(int s,int par){
    p[s]=par;
    for(int t:G[s]){
        if(par==t) continue;
        dfs1(t,s);
        cnt[s][dp[t]]+=1;
        cnt2[s][dp[t]]+=1;
    }
    rep(i,20){
        if(!cnt[s][i]) {
            dp[s]=i;
            return;
        }
    }
}

void dfs2(int s,int par,int dp_par){
    cnt2[s][dp_par]+=1;
    rep(i,20){
        if(!cnt2[s][i]){
            dp2[s]=i;
            break;
        }
    }
    for(int t:G[s]){
        if(par==t) continue;
        int x;
        rep(i,20){
            if((cnt2[s][i]-(dp[t]==i))==0){
                x=i;
                break;
            }
        }
        dfs2(t,s,x);
    }
}

void solve(){
    cin >> n >> m;
    rep(i,m) {
        cin >> a[i];
        a[i]-=1;
    }
    rep(i,n-1){
        int u,v;cin >> u >> v;u--;v--;
        G[u].push_back(v);
        G[v].push_back(u);
    }
    dfs1(0,-1);
    dfs2(0,-1,20);
    int x=0;
    rep(i,m){
        x^=dp2[a[i]];
        //cout << dp[a[i]] << endl;
    }
    if(x==0){
        cout << -1 << " " << -1 << endl;
        return;
    }
    rep(i,m){
        if((dp2[a[i]]^x)<dp2[a[i]]){
            for(int t:G[a[i]]){
                if(p[t]==a[i]){
                    if(dp[t]==(dp2[a[i]]^x)) {
                        cout << i+1 << " " << t+1 << endl;
                        return;
                    }
                }
                else{
                    cnt2[t][dp[a[i]]]-=1;
                    int y;
                    rep(j,20){
                        if(cnt2[t][j]==0) {
                            y=j;
                            break;
                        }
                    }
                    if(y==(dp2[a[i]]^x)){
                        cout << i+1 << " " << t+1 << endl;
                        return;
                    }
                }
            }
        }
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(50);
    solve();
}