#include<bits/stdc++.h>
#define pb push_back
#define P make_pair
#define fi first
#define se second
#define bit(s,x) (((s)>>(x))&1)
#define pnp(s) __builtin_popcountll(s)
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
using namespace std;
typedef long long ll; 
typedef unsigned long long ull;
typedef pair<int,int> pii;
inline ll read(){
	ll x=0,f=1,c=getchar();
	while(c<'0'||c>'9')f=(c=='-'?-1:1),c=getchar();
	while(c>='0'&&c<='9')x=(x<<1)+(x<<3)+(c^48),c=getchar();
	return x*f;
}
const int N=2e3+3;
int n,col[N];
int debug=0;
inline int ask(vector<int>vec,int i){
	++debug;
	if(n==2000)assert(debug<=6000);
	vec.pb(i);
	printf("? %d ",vec.size());
	for(int x:vec)printf("%d ",x);
	printf("\n");fflush(stdout);
	int x=read(),y=read();
	//int x=-1,y=-1;
	if(x!=-1)assert(x==i||y==i);
	if(x==i)return y;
	return x;
}
vector<int>G[N],vec[N];
int d[N];
inline void solve(int m){
	priority_queue<pii,vector<pii>,greater<pii>>q;
	static int st[N],inq[N];int tp=0;
	rep(i,1,m)q.push(P(d[i],i)),inq[i]=0;
	while(!q.empty()){
		int x=q.top().se;q.pop();
		if(inq[x])continue;
		st[++tp]=x;inq[x]=1;
		for(int j:G[x])if(!inq[j])q.push(P(--d[j],j));
	}
	while(tp){
		int i=st[tp--];
		static bool a[N];
		for(int j:G[i])a[col[j]]=1;
		for(col[i]=1;a[col[i]];++col[i]);
		for(int j:G[i])a[col[j]]=0;
		vec[col[i]].pb(i);
	}
}
int main() {
    //freopen("data.in", "r", stdin);
    //freopen("myans.out","w",stdout);
	n=read();
	rep(i,2,n){
		rep(j,1,i-1){
			col[j]=0;
			d[j]=G[j].size();
		}
		solve(i-1);
		rep(j,1,n){
			if(!vec[j].size())break;
			vector<int>tmp=vec[j];vec[j].clear();
			while(tmp.size()){
				int p=ask(tmp,i);
				if(p==-1)break;
				G[i].pb(p),G[p].pb(i);
				rep(k,0,tmp.size()-1)if(tmp[k]==p){
					swap(tmp[k],tmp.back());tmp.pop_back();
					break;
				}
			}
		}
	}
	int m=0;rep(i,1,n)m+=G[i].size();
	printf("! %d\n",m/2);
	rep(i,1,n)for(int j:G[i])if(i<j)printf("%d %d\n",i,j);
	fflush(stdout);
	cerr<<debug;
    return 0;
}