// by szh
#include<bits/stdc++.h>
using namespace std;

typedef long long LL;

#define F first
#define S second
#define pii pair<LL, LL>
#define pb push_back
#define debug(x) cerr << #x << "=" << x << endl
#define pq priority_queue
#define inf 0x3f
#define rep(i,a,b) for (int i=a; i < (b); i++)
#define MP make_pair
#define SZ(x) (static_cast<int>(x.size()))
#define MOD 1000000007
#define ALL(x) x.begin(), x.end()
void inc(int &a, int b) {a = (a+b)%MOD;}
void dec(int &a, int b) {a = (a-b+MOD)%MOD;}
int prod(int a,int b) {return LL(a)*LL(b)%MOD;}
int lowbit(int x) {return x&(-x);}

const int maxn = 555;

int n;
int deg[maxn];
vector <int> edge[maxn];

vector <int> leaf, candidate;

int main() {
  // freopen("input.txt","r",stdin);
  std::ios::sync_with_stdio(false); cin.tie(0);
  cin >> n;
  rep(i, 1, n) {
	int u, v;
	cin >> u >> v;
	edge[u].pb(v);
	edge[v].pb(u);
	deg[u]++;
	deg[v]++;
  }
  rep(i, 1, n + 1) {
	if (deg[i] == 1) leaf.pb(i);
	else candidate.pb(i);
  }
  while (SZ(candidate) > 1) {
	int mid = SZ(candidate)/2;
    cout << "? ";
    for (auto it : leaf) cout << it << " ";
    rep(i, 0, mid) cout << candidate[i] << " ";
    cout << endl;
    string s; cin >> s;
    if (s == "YES") {
	  while (SZ(candidate) > mid) candidate.pop_back();
	}
    else {
	  vector <int> tmp;
	  rep(i, mid, SZ(candidate)) tmp.pb(candidate[i]);
	  candidate = tmp;
	}
  }
  cout << "! " << candidate[0] << endl;
  return 0;
}