#include<bits/stdc++.h>
using namespace std;
#define eb emplace_back
#define Debug(...) fprintf(stderr,__VA_ARGS__)
template<typename T>
void read(T &x){
	x=0;T flg=1;
	char ch=getchar();
	while(!isdigit(ch)){if(ch=='-')flg=-1;ch=getchar();}
	while(isdigit(ch))x=(x<<3)+(x<<1)+(ch^48),ch=getchar();
	x*=flg;
}
template<typename T,typename... Args>
void read(T &x,Args &...args){read(x),read(args...);}
const int N=2e3+7;
int n,K=0,ban[N];
vector<int>s[N];
vector<pair<int,int> >e;
int main(){
	read(n);
	auto ask=[&](int u,vector<int>S){
		vector<int>Q;Q.eb(u);
		for(auto v:S)if(ban[v]!=ban[0])Q.eb(v);
		printf("? %d ",(int)Q.size());
		for(auto v:Q)printf("%d ",v);
		printf("\n");
		fflush(stdout);
	};
	for(int i=ban[0]=1;i<=n;i++,ban[0]++){
		if(i==1){s[++K].eb(1);continue;}
		else{
			int pos=0,flg=0;
			for(int j=1,p,q;j<=K;j++){
				flg=0;ask(i,s[j]);read(p,q);
				while(p!=-1){
					if(p==i)swap(p,q);
					ban[p]=ban[0];e.eb(make_pair(p,q));
					flg=1;ask(i,s[j]);read(p,q);
				}
				if(!flg&&!pos)pos=j;
			}
			if(!pos)pos=++K;
			s[pos].eb(i);
		}
	}
	if(n==2e3)assert(0);
	printf("! %d\n",(int)e.size());
	for(auto [u,v]:e)printf("%d %d\n",u,v);
	fflush(stdout);
	return 0;
}