#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Vi = std::vector<int>;
using VVi = vector<Vi>;
int main () {
    int N, M;
    cin >> N >> M;
    Vi A(M);
    for (auto& a : A) {
        cin >> a;
    }
    VVi gr(N);
    for (int s = 1; s < N; s ++) {
        int a, b;
        cin >> a >> b;
        gr[--a].push_back(--b);
        gr[b].push_back(a);
    }
    Vi tpr;
    queue<int> que;
    Vi par(N, -1);
    tpr.push_back(0);
    que.push(0);
    while (!que.empty()) {
        int u = que.front();
        que.pop();
        for (auto v : gr[u]) {
            if (v == par[u]) {
                continue;
            }
            par[v] = u;
            tpr.push_back(v);
            que.push(v);
        }
    }
    Vi dp(N);
    VVi dps(N);
    VVi sns(N);
    Vi CC(N + 10, 0);
    for (auto u : tpr) {
        for (auto v : gr[u]) {
            if (v == par[u]) {
                continue;
            }
            sns[u].push_back(dp[v]);
            CC[dp[v]] ++;
        }
        dp[u] = 0;
        while (CC[dp[u]]) {
            dp[u] ++;
        }
        for (auto v : gr[u]) {
            if (v == par[u]) {
                dps[u].push_back(-1);
            } else {
                if (dp[v] <= dp[u] && CC[dp[v]] == 1) {
                    dps[u].push_back(dp[v]);
                } else {
                    dps[u].push_back(dp[u]);
                }
            }
        }
        for (auto a : sns[u]) {
            CC[a] --;
        }
    }
    Vi dp2(N);
    dp2[0] = dp[0];
    Vi Pid(N, 0);
    for (int i = 1; i < N; i ++) {
        while (gr[i][Pid[i]] != par[i]) Pid[i] ++;
    }
    for (auto u : tpr) {
        for (auto a : sns[u]) {
            CC[a] ++;
        }
        if (u) {
            dp2[u] = 0;
            while (CC[dp2[u]]) dp2[u] ++;
        }
        for (int i = 0; i < gr[u].size(); i ++) {
            int v = gr[u][i];
            if (v != par[u]) {
                if (dp[v] <= dp2[u] && CC[dp[v]] == 1) {
                    sns[v][Pid[v]] = dp[v];
                } else {
                    sns[v][Pid[v]] = dp2[u];
                }
            }
        }
        for (auto a : sns[u]) {
            CC[a] --;
        }
    }
    int xx = 0;
    for (auto a : A) {
        xx ^= dp2[a];
    }
    if (!xx) {
        puts("-1 -1");
    } else {
        for (int i = 0; i < M; i ++) {
            int a = A[i];
            if (dp2[a] ^ xx > dp2[a]) {
                continue;
            }
            int b = 0;
            for (int j = 0; j < gr[a].size(); j ++) {
                int x = sns[a][j];
                if (dp2[a] ^ x == xx) {
                    b = gr[a][j];
                    break;
                }
            }
            printf("%d %d\n", a + 1, b + 1);
            break;
        }
    }
}