/*

Author: Haze

2024/7/28

*/

#include <bits/stdc++.h>

#define irep(i, l, r) for(int i = (l); i <= (r); ++ i)
#define drep(i, r, l) for(int i = (r); i >= (l); -- i)
#define IOS ios::sync_with_stdio(false), cin.tie(nullptr);
using namespace std;
typedef long long ll;

inline ll readL() {
    ll s = 0;
    bool fl = false;
    char ch = (char) getchar();
    while (!isdigit(ch)) {
        if (ch == '-')fl = true;
        ch = (char) getchar();
    }
    while (isdigit(ch)) {
        s = s * 10 + (ch ^ 48);
        ch = (char) getchar();
    }
    return fl ? -s : s;
}

inline int read() {
    return (int) (readL());
}

const int mod = 1000000000 + 7;
const int itinf = 1000000999;
const ll llinf = 2e18;
const int N = 500099;
int F[N], G[N];
std::mt19937 rng(std::chrono::system_clock::now().time_since_epoch().count());

int sum = 0;

vector<array<int, 2>>edge;
void submit(){
    cout << "! " << edge.size() << endl;
    for(auto [u, v] : edge){
        cout << F[u] << ' ' << F[v] << endl;
    }
    exit(0);
}

array<int, 2> query(set<int>&node){
    if(node.size() == 1){
        return {-1, -1};
    }
    if(sum == 6000){
        submit();
    }
    ++ sum;
    cout << "? " << node.size();
    for(int x : node){
        cout << " " << F[x];
    }
    cout << endl;
    array<int, 2>ar{};
    cin >> ar[0] >> ar[1];
    if(ar[0] != -1)ar[0] = G[ar[0]], ar[1] = G[ar[1]];
    return ar;
}

void solve() {
    int n;
    cin >> n;
    irep(i, 1, n)F[i] = i, G[i] = i;
    shuffle(F + 1, F + n + 1, rng);
    irep(i, 1, n){
        G[F[i]] = i;
    }
    vector<set<int>>col = {{1}};

    irep(u, 2, n){
        int to = -1;
        irep(c, 0, col.size() - 1){
            auto vec = col[c];
            vec.emplace(u);
            auto [i, j] = query(vec);
            if(i == -1){
                if(to == -1 or col[to].size() < col[c].size()){
                    to = c;
                }
            }

            while(i != -1){
                edge.push_back({i, j});

                vec.erase(i + j - u);
                auto T = query(vec);
                i = T[0], j = T[1];
            }
        }
        if(to == -1){
            col.push_back({u});
        }
        else col[to].insert(u);
    }
    submit();
}

int main() {
    // IOS
    int T = 1;
    while (T--) {
        solve();
    }
    return 0;
}