using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	static List<int>[] li;
	static List<(int,int)>[] lih;
	static bool[] b;
	static int[] h,d,oa,op;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		int n=s[0],m=n-1;
		if(n==1){
			Console.WriteLine("-1 -1");
			return;
		}
		li=new List<int>[n+1];
		lih=new List<(int,int)>[n+1];
		b=new bool[n+1];
		h=new int[n+1];
		d=new int[20];
		oa=new int[n+1];
		op=new int[n+1];
		var a=sc.Ia;
		for(int i=1;i<=n;i++){
			li[i]=new List<int>();
			lih[i]=new List<(int,int)>();
		}
		for(int i=0;i<m;i++){
			var e=sc.Ia;
			li[e[0]].Add(e[1]);
			li[e[1]].Add(e[0]);
		}
		int o=1;
		for(int i = 1;i<=n;i++) {
			if(li[i].Count==1){
				o=i;
				break;
			}
		}
		Fu(o,0);
		b=new bool[n+1];
		Fu2(li[o][0],0);
		int ans=0;
		for(int i = 0;i<s[1];i++) {ans^=h[a[i]];}

		if(ans==0){Console.WriteLine("-1 -1");}
		else{
			for(int i = 0;i<s[1];i++) {
				if(oa[i]!=0&&(ans^h[a[i]]^op[a[i]])==0){
					Console.WriteLine("{0} {1}",i+1,op[i]);
					return;
				}
				for(int j = 0;j<lih[a[i]].Count;j++) {
					if(lih[a[i]][j].Item2==0){break;}
					if((ans^h[a[i]]^lih[a[i]][j].Item1)==0){
						Console.WriteLine("{0} {1}",i+1,lih[a[i]][j].Item2);
						return;
					}
				}
			}
		}
	}
	static void Fu2(int a,int p){
		b[a]=true;
		op[a]=p;
		d=new int[20];
		d[p]++;
		
		for(int i = 0;i<lih[a].Count;i++) {d[lih[a][i].Item1]++;}
		for(int i = 0;i<d.Length;i++) {
			if(d[i]==0){
				h[a]=i;
				break;
			}
		}
		for(int i = 0;i<lih[a].Count;i++) {
			if(d[lih[a][i].Item1]>1){
				Fu2(lih[a][i].Item2,h[a]);
			}
			else{
				Fu2(lih[a][i].Item2,Min(h[a],lih[a][i].Item1));
			}
			
		}
	}
	static int Fu(int a,int p){
		b[a]=true;
		oa[a]=p;
		for(int i=0;i<li[a].Count;i++){
			if(!b[li[a][i]]){
				lih[a].Add((Fu(li[a][i],a),li[a][i]));
			}
		}
		for(int i = 0;i<lih[a].Count;i++) {d[lih[a][i].Item1]=a;}
		for(int i = 0;;i++) {
			if(d[i]!=a){
				h[a]=i;
				break;
			}
		}
		return h[a];
	}
}

public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}