#include <bits/stdc++.h>
using namespace std;

#define int long long
#define pii pair<int, int>
#define ff first
#define ss second

const int MAXN = 2e3 + 5;

int n;
vector<int> adj[MAXN];
int color[MAXN], used[MAXN];
set<int> sets[MAXN];

pii ask(set<int> nodes) {
	cout << "? " << nodes.size() << " ";

    for(auto node : nodes) cout << node << " ";
    cout << endl;

    int a, b; cin >> a >> b;
    return {min(a, b), max(a, b)};
}

void magic(int u) {
	for(auto v : adj[u]) {
		if(color[v] != 0) used[color[v]] = u;
	}

	for(int c = 1; c <= n; ++c) {
		if(used[c] != u) {
			color[u] = c; sets[u].insert(c);
			break;
		}
	}

	for(auto v : adj[u]) {
		if(color[v] == 0) magic(v);
	}
}

signed main() {
	cin.tie(0)->sync_with_stdio(false);
	cin >> n;

	vector<pii> ans;

	for(int i = 2; i <= n; ++i) {
		for(int j = 1; j <= n; ++j) {
			color[i] = used[i] = 0;
			sets[j].clear();
		}

		for(int j = 1; j < i; ++j) {
			if(color[j] == 0) magic(j);
		}

		for(int c = 1; c <= n; ++c) {
			if(sets[c].empty()) break;

			sets[c].insert(i);

			pii edge = ask(sets[c]);

			while(edge.ff != -1) {
				ans.push_back(edge);
				adj[edge.ff].push_back(edge.ss); adj[edge.ss].push_back(edge.ff);
				sets[c].erase(edge.ff);

				if(sets[c].size() < 2) break;

				edge = ask(sets[c]);
			}
		}
	}

	cout << "! " << ans.size() << endl;
	for(auto edge : ans) cout << edge.ff  << " " << edge.ss << endl;
}