// 15:36 - 15:56
#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define lch (o << 1)
#define rch (o << 1 | 1)

typedef double db;
typedef long long ll;
typedef unsigned int ui;
typedef pair<int, int> pint;
typedef tuple<int, int, int> tint;

const int N = 2e5 + 5;
const int K = 18 + 2;
const int INF = 0x3f3f3f3f;
const ll INF_LL = 0x3f3f3f3f3f3f3f3f;

vector<int> a[N];
int sg[N], cnt[N][K];
int rt[N], nxt[N][K];
int pos[N];

int Mex(int cnt[]) {
	for (int i = 0; i < K; i++)
		if (cnt[i] == 0)
			return i;
	return -1; // impossible
}

void DFS(int u, int pa) {
	for (auto v: a[u]) {
		if (v == pa) continue;
		DFS(v, u);
		cnt[u][sg[v]]++;
	}
	sg[u] = Mex(cnt[u]);
}

void Cal(int u, int pa, int sgPa) {
	// update sg(u)
	if (sgPa != -1) {
		nxt[u][sgPa] = pa;
		cnt[u][sgPa]++;
		sg[u] = Mex(cnt[u]);
	}
	rt[u] = sg[u];

	// top-down
	for (auto v: a[u]) {
		if (v == pa) continue;
		nxt[u][sg[v]] = v;
		cnt[u][sg[v]]--;
		int sgNew = cnt[u][sg[v]] ? sg[u] : sg[v];
		Cal(v, u, sgNew);
		cnt[u][sg[v]]++;
	}

	// restore sg(u)
	if (sgPa != -1) {
		cnt[u][sgPa]--;
		sg[u] = Mex(cnt[u]);
	}
}

int main() {
	ios::sync_with_stdio(0);

	int n, m;
	cin >> n >> m;
	for (int i = 1; i <= m; i++)
		cin >> pos[i];
	for (int i = 1; i < n; i++) {
		int u, v;
		cin >> u >> v;
		a[u].push_back(v);
		a[v].push_back(u);
	}
	DFS(1, 0);
	Cal(1, 0, -1);

	int sgSum = 0;
	for (int i = 1; i <= m; i++)
		sgSum ^= rt[pos[i]];
	if (sgSum == 0) {
		cout << "-1 -1" << endl;
		return 0;
	}

	for (int i = 1; i <= m; i++) {
		int u = pos[i];
		int need = rt[u] ^ sgSum;
		if (need >= K) continue;
		if (nxt[u][need]) {
			cout << i << ' ' << nxt[u][need] << endl;
			return 0;
		}
	}

	return 0;
}