#include "bits/stdc++.h" using namespace std; #define int long long #define REP(i, n) for (int i = 0; i < (int)n; ++i) #define RREP(i, n) for (int i = (int)n - 1; i >= 0; --i) #define FOR(i, s, n) for (int i = s; i < (int)n; ++i) #define RFOR(i, s, n) for (int i = (int)n - 1; i >= s; --i) #define ALL(a) a.begin(), a.end() #define IN(a, x, b) (a <= x && x < b) templateistream&operator >>(istream&is,vector&vec){for(T&x:vec)is>>x;return is;} templateinline void out(T t){cout << t << "\n";} templateinline void out(T t,Ts... ts){cout << t << " ";out(ts...);} templateinline bool CHMIN(T&a,T b){if(a > b){a = b;return true;}return false;} templateinline bool CHMAX(T&a,T b){if(a < b){a = b;return true;}return false;} constexpr int INF = 1e18; signed main(){ int N, M; cin >> N >> M; vectora(M); cin >> a; REP(i, M) --a[i]; vector>g(N); REP(i, N - 1) { int a, b; cin >> a >> b; --a; --b; g[a].emplace_back(b); g[b].emplace_back(a); } vectordp(N); //falseは行動すると負け { auto dfs = [&](auto&&f, int now, int par) -> bool { int ret = 0, child = 0; for(auto e: g[now]) { if(e == par) continue; ++child; if(f(f, e, now) == false) ret = true; } return dp[now] = ret; }; dfs(dfs, 0, -1); } vectorv(N); vectordp2(N); { auto dfs = [&](auto&&f, int now, int par, int par_val) -> void { //自分を親と見た時の結果を集計する int child = 0, end = 0;; for(auto e: g[now]) { if(e == par && par != -1){ if(!par_val){ ++end; v[now] = par; } continue; } ++child; if(!dp[e]){ ++end; v[now] = e; } } if(end)dp2[now] = true; for(auto e: g[now]) { if(e == par) continue; int flg = 0; if(end > 1)flg = true; else if(end == 1 && dp[e] == true) flg = true; else flg = false; f(f, e, now, flg); } }; dfs(dfs, 0, -1, 0); } int ans = 0; REP(i, M) { if(dp[a[i]]) ans ^= 1; } if(ans == 0) out(-1, -1); else { REP(i, M) { if(dp[i] == false) continue; for(auto e: g[i]) { if(dp2[e] == true) { out(i + 1, v[i] + 1); exit(EXIT_SUCCESS); } } } } }