#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second

using namespace std;
using ii = pair <int, int>;
using vi = vector <int>;

ii qry(vi &g){
    if (g.size() == 1) return ii(-1, -1);
    cout << "? " << g.size() << ' ';
    for (int u : g) cout << u << ' ';
    cout << endl;
    ii ans; cin >> ans.fi >> ans.se;
    return ans;
}

vector <ii> edges;

const int N = 2005;

bool e[N][N];

void add(int u, int v){
    e[u][v] = e[v][u] = 1;
    edges.pb({u, v});
}

void solve(vector <int> p){
    if (p.size() == 1) return;
    vector <int> s, t;
    for (int u : p){
        s.pb(u);
        auto [g, k] = qry(s);
        if (g != -1) s.pop_back(), t.pb(u), add(g, k);
    }

    for (int u : t){
        vi ask = {u};
        for (int v : s) if (!e[u][v]) ask.pb(v);
        auto [g, k] = qry(ask);
        if (g == -1) break;
        add(g, k);
    }

    solve(t);
}

int main(){
    int n; cin >> n;

    vector <int> p(n);
    iota(p.begin(), p.end(), 1);
    solve(p);

    cout << "! " << edges.size() << endl;
    for (auto [u, v]: edges) cout << u << ' ' << v << endl;


    return 0;
}