#include<bits/stdc++.h>
using namespace std;
constexpr int M=2005;bool vis[M];
int n,num,col[M],tmp[M],deg[M];
vector<pair<int,int>>ans;
vector<int>res[M],adj[M];
struct info{ int val,pos;
    bool operator <(const info &a) const
        {return a.val<val;}
};
pair<int,int> query(vector<int>&qry){
    if (qry.size()<2) return make_pair(-1,-1);
    cout<<"? "<<qry.size(); for (auto x:qry) cout<<' '<<x; cout<<'\n';
    int x,y; cin>>x>>y;
    if (!~x) return make_pair(-1,-1);
    adj[x].emplace_back(y);
    adj[y].emplace_back(x);
    ans.emplace_back(x,y);
    return minmax(x,y);
}
void build(int n){
    vector<int>rec; priority_queue<info>q; num=0;
    for (int i=1;i<=n;i++) col[i]=-1,vis[i]=tmp[i]=0,res[i].clear();
    for (int i=1;i<=n;i++) q.push({deg[i]=adj[i].size(),i});
    while (!q.empty()){
        auto [val,x]=q.top();q.pop();
        if (vis[x]) continue;
        vis[x]=1;rec.emplace_back(x);
        for (auto y:adj[x]) q.push({--deg[y],y});
    }
    reverse(rec.begin(),rec.end());
    for (auto x:rec){
        for (auto y:adj[x])
            if (~col[y]) tmp[col[y]]=x;
        for (int i=1;i<=n;i++)
            if (tmp[i]!=x) {col[x]=i;break;}
        res[col[x]].emplace_back(x);num=max(num,col[x]);
    }
}
int main(){ cin>>n;
    for (int i=1;i<=n;i++){
        for (int j=1;j<=num;j++){
            res[j].emplace_back(i);
            int x=query(res[j]).first;
            while (~x){
                res[j].erase(lower_bound(res[j].begin(),res[j].end(),x));
                x=query(res[j]).first;
            }
        }
        build(i);
    }
    cout<<"! "<<ans.size()<<'\n';
    for (auto [x,y]:ans) cout<<x<<' '<<y<<'\n';
    return 0;
}