#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vec<T>>;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N,M;
    cin >> N >> M;
    vec<int> A(M);
    set<int> s;
    for(int i=0;i<M;i++){
        cin >> A[i];
        A[i]--;
        s.insert(A[i]);
    }
    vvec<int> g(N);
    for(int i=0;i<N-1;i++){
        int a,b;
        cin >> a >> b;
        a--; b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    vec<int> dp(N);
    
    {
        auto dfs = [&](auto&& self,int cur,int par)->void{
            bool exist = false;
            for(auto& to:g[cur]) if(to!=par){
                self(self,to,cur);
                exist |= !dp[to];
            }
            dp[cur] = exist;
        };
        dfs(dfs,0,-1);
    }
    vec<int> dp2(N);
    vvec<int> child[2];
    for(int i=0;i<2;i++) child[i] = vvec<int>(N);
    {
        auto dfs = [&](auto&& self,int cur,int par,int parg)->void{
            int n = g[cur].size();
            vec<int> L(n+1,0),R(n+1,0);
            for(int i=0;i<n;i++){
                int to = g[cur][i];
                L[i+1] = L[i] || !(to!=par? dp[to]:parg);
            }
            for(int i=n-1;i>=0;i--){
                int to = g[cur][i];
                R[i] = R[i+1] || !(to!=par? dp[to]:parg);
            }
            dp2[cur] = L[n];
            for(int i=0;i<n;i++){
                int to = g[cur][i];
                child[(to!=par? dp[to]:parg)][cur].push_back(to);
                if(to==par) continue;
                self(self,to,cur,L[i]||R[i+1]);
            }
        };
        dfs(dfs,0,-1,0);
    }

    int win = 0;
    for(int i=0;i<M;i++) win ^= dp2[A[i]];
    if(!win){
        cout << -1 << " " << -1 << "\n";
        return 0;
    }
    assert(false);
    for(int i=0;i<M;i++){
        for(auto& x:child[!dp2[A[i]]][A[i]]){
            cout << i+1 << " " << x+1 << "\n";
            return 0;
        }
    }
}