#include <bits/stdc++.h>
#define f first
#define s second
#define mp make_pair
using namespace std;
typedef long long ll;
const ll mod = 1e9 + 7;
// Cope Counter = at least 147

int n;
vector<int> adj[2001];
set<int> bk[2001];
int color[2001], vis[2001];

void kms(int i) {
  for(auto j : adj[i]) {
    if(color[j] >= 0) vis[color[j]] = i;
  }
  for(int j = 0; j < n; j++) {
    if(vis[j] != i) {
      color[i] = j;
      bk[j].insert(i);
      break;
    }
  }
  for(auto j : adj[i]) {
    if(color[j] < 0) kms(j);
  }
}
pair<int, int> qry(set<int> pts) {
  cout << "? " << pts.size();
  for(int i : pts) cout << " " << i + 1;
  cout << "\n";
  cout.flush();
  pair<int, int> e;
  cin >> e.f >> e.s;
  if(e.f > e.s) swap(e.f, e.s);
  return e;
}

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
  cin >> n;
  vector<pair<int, int>> edges;
  for(int i = 1; i < n; i++) {
    for(int j = 0; j < n; j++) {
      bk[j].clear();
      color[j] = vis[j] = -1;
    }
    for(int j = 0; j < i; j++) {
      if(color[j] < 0) kms(j);
    }
    for(int j = 0; j < n; j++) {
      if(bk[j].empty()) break;
      bk[j].insert(i);
      auto e = qry(bk[j]);
      while(e.f >= 0) {
        edges.push_back(e);
        adj[e.f - 1].push_back(e.s - 1);
        adj[e.s - 1].push_back(e.f - 1);
        bk[j].erase(e.f - 1);
        if(bk[j].size() < 2) break;
        e = qry(bk[j]);
      }
    }
  }
  cout << "! " << edges.size() << "\n";
  for(auto i : edges) cout << i.f << " " << i.s << "\n";
  cout.flush();
}