#include <bits/stdc++.h>
#define For(i,a,b) for(int i=a;i<=b;i++)
#define Rev(i,a,b) for(int i=a;i>=b;i--)
#define Fin(file) freopen(file,"r",stdin)
#define Fout(file) freopen(file,"w",stdout)
using namespace std; using ll = long long;
const int N=2e3+5; using pii = pair<int,int>;
int n,col[N],vis[N],deg[N],mxcol; vector<pii> ans; vector<int> lis[N],to[N];
int Cnt=0;
pii query(const vector<int>& vec){
	if(n==2000) assert((++Cnt)<=6000);
	cout<<"? "<<vec.size()<<' '; for(int x:vec) cout<<x<<' ';; cout<<'\n'; cout.flush();
	int x,y; if(!(cin>>x>>y)) exit(0);; return pii(x,y);
}
void rework(int lim){
	int mn=0; For(i,1,lim) if(deg[i]<deg[mn]&&col[i]==-1) mn=i;
	if(mn==0) return;
	col[mn]=0; for(int v:to[mn]) deg[v]--;
	rework(lim);
	For(i,1,mxcol) vis[i]=0;
	for(int v:to[mn]) vis[col[v]]=1;
	For(i,1,mxcol+1) if(!vis[i]) { col[mn]=i; break; } 
	mxcol=max(mxcol,col[mn]);
}
int main(){
	cin>>n; col[1]=mxcol=1;
	For(u,2,n){
		For(i,1,mxcol) lis[i].clear(),vis[i]=0;
		For(v,1,u-1) lis[col[v]].push_back(v);
		For(i,1,mxcol) if(lis[i].size()){
			vector<int> tmp=lis[i]; tmp.push_back(u);
			while(tmp.size()>1u){
				auto pr=query(tmp);
				if(pr.first==-1||pr.second==-1) break;
				int v=pr.first^pr.second^u;
				ans.push_back(minmax(u,v)); to[u].push_back(v); to[v].push_back(u);
				tmp.erase(find(tmp.begin(),tmp.end(),v));
			}
		}
		deg[0]=1e9; For(i,1,u) deg[i]=to[i].size(),col[i]=-1;; rework(u);
		//~ for(auto pr:ans) assert(col[pr.first]!=col[pr.second]);
	}
	cout<<"! "<<ans.size()<<'\n';
	for(auto pr:ans) cout<<pr.first<<' '<<pr.second<<'\n';
	return 0;
}