#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=1167167167167167167;
const int INF=2100000000;
const ll mod=1e9+7;
#define rep(i,a) for (ll i=0;i<a;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}

std::vector<std::vector<int>> tree_in(int N){
	std::vector<std::vector<int>> G(N);
	for(int i=0;i<N-1;i++){
		int a;int b;
		cin>>a>>b; 
		a--,b--;
		G[a].push_back(b);
		G[b].push_back(a);
	}
	return G;
}
std::tuple<std::vector<int>,std::vector<int>,std::vector<int>> tree_order_pare_depth(std::vector<std::vector<int>> &G,int root){
	int n=G.size();
	std::vector<int> order={root},pare(n,-1),depth(n);
	pare[root]=-2;
	for(int i=0;i<n;i++){
		int a=order[i];
		for(auto x:G[a]){
			if(pare[x]==-1){
				pare[x]=a;
				depth[x]=depth[a]+1;
				order.push_back(x);
			}
		}
	}
	return {order,pare,depth};
}
std::vector<int> tree_diameter_path(std::vector<std::vector<int>> &G){
	int n=G.size();
	auto r=(std::get<0>(tree_order_pare_depth(G,0))).at(n-1);
	std::vector<int> order,pare,depth,ans;
	tie(order,pare,depth)=tree_order_pare_depth(G,r);
	int ind=order[n-1];
	while(ind!=-2){
		ans.push_back(ind);
		ind=pare[ind];
	}
	return ans;
}


void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	int N,M;
	cin>>N>>M;
	vector<int> p(M);
	rep(i,M) cin>>p[i],p[i]--;
	map<pair<int,int>,int> m;
	auto G=tree_in(N);
	vector<int> order,pare,dp2;
	tie(order,pare,dp2)=tree_order_pare_depth(G,0);
	dp2[0]=N;
	vector<int> table(N+1),dp(N),dp3(N);
	set<int> s;
	rep(i,N){
		int a=order[N-i-1];
		for(auto x:G[a]){
			if(pare[x]==a){
				table[dp[x]]++;
				s.insert(dp[x]);
			}
		}
		rep(j,N+1){
			if(table[j]==0){
				dp[a]=j;
				break;
			}
		}
		for(auto x:s) table[x]=0;
		s={};
	}
	rep(i,N){
		int a=order[i];
		for(auto x:G[a]){
			if(pare[x]==a){
				table[dp[x]]++;
				s.insert(dp[x]);
			}
		}
		table[dp2[a]]++;
		s.insert(dp2[a]);
		int X=-1;
		rep(i,N+1){
			if(table[i]==0){
				X=i;
				break;
			}
		}
		//cout<<"$"<<a+1<<" "<<X<<endl;
		for(auto x:G[a]){
			if(pare[x]==a){
				//cout<<dp[x]<<" "<<table[dp[x]]<<endl;
				if(table[dp[x]]==1) dp2[x]=min(dp[x],X);
				else dp2[x]=X;
			}
		}
		for(auto x:s) table[x]=0;
		s={};
	}
	int ans=0;
	rep(y,N){
		for(auto x:G[y]){
			if(pare[x]==y){
				table[dp[x]]++;
				s.insert(dp[x]);
			}
		}
		table[dp2[y]]++;
		s.insert(dp2[y]);
		rep(i,N+1){
			if(table[i]==0){
				dp3[y]=i;
				break;
			}
		}
		for(auto x:s) table[x]=0;
		s={};
	}
	rep(i,M) ans^=dp3[p[i]];
	/*rep(i,N){
		cout<<dp[i]<<" "<<dp2[i]<<" "<<dp3[i]<<endl;
	}*/
	if(ans==0){
		cout<<"-1 -1\n";
		return;
	}
	set<int> ban;
	rep(i,M){
		int y=p[i];
		if(ban.count(y)) continue;
		ban.insert(y);
		if(y!=0&&(ans^dp2[y]^dp3[y])==0){
			cout<<i+1<<" "<<pare[y]+1<<"\n";
			return;
		}
		for(auto x:G[y]){
			if(pare[x]==y){
				if((ans^dp3[y]^dp[x])==0){
					cout<<i+1<<" "<<x+1<<"\n";
					return;
				}
			}
		}
	}
}