from collections import deque
import sys
input = lambda: sys.stdin.readline().rstrip()
N, M = map(int, input().split())
A = [int(a) - 1 for a in input().split()]
X = [[] for i in range(N)]
for _ in range(N - 1):
    x, y = map(int, input().split())
    X[x-1].append(y-1)
    X[y-1].append(x-1)
P = [-1] * N
Q = deque([0])
R = []
while Q:
    i = deque.popleft(Q)
    R.append(i)
    for a in X[i]:
        if a != P[i]:
            P[a] = i
            X[a].remove(i)
            deque.append(Q, a)

G = [0] * N # Grundy Number
L = [[] for _ in range(N)]
for i in R[::-1]:
    m = min(len(X[i]) + 2, 20)
    L[i] = [0] * m
    for j in X[i]:
        if G[j] < m:
            L[i][G[j]] += 1
    for k in range(m):
        if not L[i][k]:
            G[i] = k
            break
G_bu = G[:]
for i in R[1:]:
    m = min(len(X[i]) + 2, 20)
    g = G[i]
    p = P[i]
    pg = G[p]
    if g < pg and L[p][g] == 1:
        pg = g
    if pg < m:
        L[i][pg] += 1
    if pg == g:
        for k in range(g, m):
            if not L[i][k]:
                G[i] = k
                break

s = 0
for a in A:
    s ^= G[a]

if s == 0:
    print(-1, -1)
else:
    for i, a in enumerate(A):
        if G[a] ^ s < G[a]:
            for b in X[a]:
                if G[a] ^ s == G_bu[b]:
                    print(i+1, b+1)
                    exit()
            print(i+1, P[a] + 1)
            exit()