from collections import deque

def question(X):
    print("?", *[x+1 for x in X])
    return input()

def answer(n):
    print("!", n+1)

N = int(input())
G = [[] for _ in range(N)]
edge = []
for _ in range(N-1):
    u, v = map(int, input().split())
    u, v = u-1, v-1
    edge.append((u, v))
    G[u].append(v)
    G[v].append(u)

que = deque()
que.append(0)
color = [-1]*N
color[0] = 0
while que:
    n = que.popleft()
    for v in G[n]:
        if color[v] == -1:
            color[v] = color[n]^1
            que.append(v)

C = -1
A = []
for u, v in edge:
    if color[u] == 0:
        A.append(u)
    else:
        A.append(v)
ans = question(A)
if ans == "Yes":
    C = 0
else:
    C = 1

IDX = [i for i in range(N) if color[i] == C]
left = 0
right = len(IDX)
while left+1 < right:
    mid = (left+right)//2
    A = []
    S = set(IDX[left:mid])
    for u, v in edge:
        if u in S:
            A.append(u)
            continue
        if v in S:
            A.append(v)
            continue
        if color[u] == C:
            A.append(v)
        else:
            A.append(u)
    if question(A) == "No":
        left = mid
    else:
        right = mid

answer(IDX[left])