#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define fo(i,a,b) for(int i=a;i<=b;++i)
#define fod(i,a,b) for(int i=a;i>=b;--i)
int n;
int d[511],px[511];
bool cmp(int x,int y){
	return (d[x]<d[y]);
}
int main(){
	cin>>n;
	fo(i,1,n-1){
		int x,y;
		cin>>x>>y;
		++d[x],++d[y];
	}
	fo(i,1,n)px[i]=i;
	sort(px+1,px+n+1,cmp);
	int w=1;
	while(w<n&&d[px[w+1]]==1)++w;
	int l=1,r=n;
	char s[10];
	while(l<r&&r>2){
		int mid=(l+r)/2;
		cout<<"? ";
		if(mid<=w){	
			cout<<mid-l+1<<" ";
			fo(i,l,mid)cout<<px[i]<<" ";
			cout<<endl;	
		}
		else{
			cout<<w+max(0,mid-max(l,w+1)+1)<<" ";
			fo(i,1,w)cout<<px[i]<<" ";
			fo(i,max(l,w+1),mid)cout<<px[i]<<" ";
			cout<<endl;
		}
		cout.flush();
		cin>>s;
		if(s[0]=='N')l=mid+1;
		else r=mid;
	}
	if(r==2){
		cout<<"? "<<n-1<<" ";
		fo(i,2,n)cout<<px[i]<<" ";
		cout<<endl;
		cout.flush();
		cin>>s;
		if(s[0]=='N')l=2;
	}
	cout.flush();
	cout<<"! "<<px[l];
	cout.flush();
	return 0;
}