#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n, m; cin >> n >> m;
  vector<int> a(m); REP(i, m) cin >> a[i], --a[i];
  vector<vector<int>> graph(n);
  REP(_, n - 1) {
    int u, v; cin >> u >> v; --u; --v;
    graph[u].emplace_back(v);
    graph[v].emplace_back(u);
  }
  vector<vector<pair<int, int>>> chi(n);
  function<int(int, int)> pre = [&](int par, int ver) {
    set<int> st;
    for (int e : graph[ver]) {
      if (e == par) continue;
      int d = pre(ver, e);
      st.emplace(d);
      chi[ver].emplace_back(d, e);
    }
    int res = 0;
    while (st.count(res) == 1) ++res;
    return res;
  };
  pre(-1, 0);
  vector<int> gru(n);
  function<void(int, int, int)> dfs = [&](int par, int ver, int par_val) {
    if (par_val >= 0) chi[ver].emplace_back(par_val, par);
    map<int, vector<int>> mp;
    for (auto [val, dst] : chi[ver]) mp[val].emplace_back(dst);
    map<int, int> children;
    gru[ver] = 0;
    while (mp.count(gru[ver]) == 1) {
      if (mp[gru[ver]].size() == 1) children[mp[gru[ver]][0]] = gru[ver];
      ++gru[ver];
    }
    for (int e : graph[ver]) {
      if (e != par) dfs(ver, e, children.count(e) == 1 ? children[e] : gru[ver]);
    }
  };
  dfs(-1, 0, -1);
  int x = 0;
  REP(i, m) x ^= gru[a[i]];
  if (x > 0) {
    vector visited(n, false);
    REP(i, m) {
      if (visited[a[i]]) continue;
      visited[a[i]] = true;
      for (auto [val, dst] : chi[a[i]]) {
        if ((x ^ gru[a[i]] ^ val) == 0) {
          cout << i + 1 << ' ' << dst + 1 << '\n';
          return 0;
        }
      }
    }
    assert(false);
  }
  cout << "-1 -1\n";
  return 0;
}