#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;

bool ask(const set<int> &s, pair<int,int> &e) {
    if (s.size() <= 1) {
        return false;
    }

    printf("? %d", (int)s.size());
    for (int x: s)
        printf(" %d", x);
    printf("\n");
    fflush(stdout);
    scanf("%d%d", &e.first, &e.second);
    return not (e.first == -1 && e.second == -1);
}

vector<int> ask_edges(set<int> &st, int i) {
    pair<int,int> e;
    vector<int> adj;
    while (ask(st, e)) {
        int j = e.first == i ? e.second : e.first;
        adj.push_back(j);
        st.erase(j);
    }
    for (int j: adj) st.insert(j);
    return adj;
}

vector<pair<int,int>> ans;
int pa[2001];
void gao(set<int> st) {
    if (st.size() <= 1)
        return;

    vector<int> ind;
    pair<int,int> e;
    // cerr << "new gao\n";
    while (ask(st, e)) {
        int i = e.first;
        st.erase(i);
        ind.push_back(i);
        ans.emplace_back(e);
        pa[i] = e.second;
    }
    for (int i: ind) {
        int p = pa[i];
        while (not st.count(p))
            p = pa[p];
        st.erase(p);
        st.insert(i);
        for (int j: ask_edges(st, i))
            ans.emplace_back(i, j);
        st.erase(i);
        st.insert(p);
    }
    gao(set<int>(ind.begin(), ind.end()));
}

int main() {
    // cin.tie(nullptr)->sync_with_stdio(false);
    int n;
    scanf("%d", &n);

    set<int> st;
    for (int i = 1; i <= n; i++)
        st.insert(i);
    gao(st);

    for (auto &[a, b]: ans)
        if (a > b) swap(a, b);
    sort(ans.begin(), ans.end());
    ans.erase(unique(ans.begin(), ans.end()), ans.end());

    printf("! %d\n", (int)ans.size());
    for (auto [a, b]: ans)
        printf("%d %d\n", a, b);

    return 0;
}