#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define piii tuple<int,int,int>
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define deb(var) cerr<<#var<<'='<<(var)<<"; "
#define int long long
int n,deg[510],p[510]; 
int Q(int k){
	if(k==1){
		cout<<"? 2 "<<p[1]<<' '<<p[3];
	}else{
		cout<<"? "<<k<<' ';
		for(int i=1;i<=k;i++)cout<<p[i]<<' ';
	}
	cout<<endl;
	string x;cin>>x;return x[0]=='Y'; 
}
void work(){
	cin>>n;
	for(int i=1,u,v;i<n;i++){
		cin>>u>>v;deg[u]++,deg[v]++;
	}
	iota(p+1,p+n+1,1);
	random_shuffle(p+1,p+n+1); 
	sort(p+1,p+n+1,[&](int i,int j){return mp(deg[i],i)<mp(deg[j],j);});
	int l=1,r=n;
	while(l<r){
		int mid=(l+r)>>1;
		if(Q(mid))r=mid;else l=mid+1;
	}cout<<"! "<<p[l]<<endl;
}
signed main(){
	ios::sync_with_stdio(0),
	cin.tie(0),cout.tie(0);
	int T=1;while(T--)work();return 0;
}