#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; //#define int long long typedef long long ll; typedef unsigned long long ul; typedef unsigned int ui; constexpr ll mod = 1000000007; const ll INF = mod * mod; typedef pairP; #define stop char nyaa;cin>>nyaa; #define rep(i,n) for(int i=0;i=0;i--) #define Rep(i,sta,n) for(int i=sta;i=1;i--) #define Rep1(i,sta,n) for(int i=sta;i<=n;i++) #define all(v) (v).begin(),(v).end() typedef pair LP; typedef long double ld; typedef pair LDP; const ld eps = 1e-12; const ld pi = acos(-1.0); ll mod_pow(ll x, ll n, ll m) { ll res = 1; while (n) { if (n & 1)res = res * x % m; x = x * x % m; n >>= 1; } return res; } struct modint { ll n; modint() :n(0) { ; } modint(ll m) :n(m) { if (n >= mod)n %= mod; else if (n < 0)n = (n % mod + mod) % mod; } operator int() { return n; } }; bool operator==(modint a, modint b) { return a.n == b.n; } modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; } modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; } modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; } modint operator+(modint a, modint b) { return a += b; } modint operator-(modint a, modint b) { return a -= b; } modint operator*(modint a, modint b) { return a *= b; } modint operator^(modint a, ll n) { if (n == 0)return modint(1); modint res = (a * a) ^ (n / 2); if (n % 2)res = res * a; return res; } ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); } modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); } const int max_n = 1 << 17; modint fact[max_n], factinv[max_n]; void init_f() { fact[0] = modint(1); for (int i = 0; i < max_n - 1; i++) { fact[i + 1] = fact[i] * modint(i + 1); } factinv[max_n - 1] = modint(1) / fact[max_n - 1]; for (int i = max_n - 2; i >= 0; i--) { factinv[i] = factinv[i + 1] * modint(i + 1); } } modint comb(int a, int b) { if (a < 0 || b < 0 || a < b)return 0; return fact[a] * factinv[b] * factinv[a - b]; } const int mn = 1 << 18; struct edge { int to; }; using Data = int; vector G[mn]; vector ids[mn]; vector memo[mn]; int root; int mex(vector v) { sort(all(v)); v.erase(unique(all(v)), v.end()); rep(i, v.size())if (i != v[i])return i; return v.size(); } int pars[mn]; Data dfs(int id, int fr) { pars[id] = fr; Data res; vector v; // //initialize // for (edge e : G[id]) { if (e.to == fr)continue; Data nex = dfs(e.to, id); // //update with edge // v.push_back(nex); ids[id].push_back(e.to); memo[id].push_back(nex); } // //update for return res = mex(v); // return res; } int grandy[mn]; int pargrandy[mn]; void invdfs(int id, int fr, Data pre) { vector v; for (Data d : memo[id])v.push_back(d); if (fr >= 0)v.push_back(pre); int len = v.size(); // //calcurate id's ans grandy[id] = mex(v); // // Data init_c = 0; // vector cnt(len + 1); rep(i, len) { if (v[i] <= len)cnt[v[i]]++; } int ag = 0; rep(i, len+1)if (cnt[i] == 0) { ag = i; break; } rep(i, ids[id].size()) { int to = ids[id][i]; int val = ag; if (v[i] <= len && cnt[v[i]] == 1) { val = min(val, v[i]); } // //update for return // pargrandy[to] = id; invdfs(to, id, val); } } void yaru() { dfs(root, -1); invdfs(root, -1, 0); } void solve() { int n; cin >> n; int m; cin >> m; vector a(m); rep(i, m) { cin >> a[i]; a[i]--; } rep(i, n - 1) { int a, b; cin >> a >> b; a--; b--; G[a].push_back({ b }); G[b].push_back({ a }); } yaru(); int x = 0; int ma = -1; int chk = -1; rep(i, m) { x ^= grandy[a[i]]; if (ma < grandy[a[i]]) { ma = grandy[a[i]]; chk = i; } } if (x == 0) { cout << -1 << " " << -1 << "\n"; } else { int y = x ^ grandy[a[chk]]; if (pargrandy[a[chk]] == y) { cout << chk + 1 << " " << pars[a[chk]] + 1 << "\n"; } else { rep(j, ids[a[chk]].size()) { if (memo[a[chk]][j] == y) { cout << chk + 1 << " " << ids[a[chk]][j] + 1 << "\n"; return; } } assert(false); } } } signed main() { //ios::sync_with_stdio(false); //cin.tie(0); cout << fixed << setprecision(10); //init_f(); //expr(); //int t; cin >> t; rep(i, t) solve(); return 0; }