/*

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;

array<int, 2> query(vector<int>&node){
    if(node.size() == 1){
        return {-1, -1};
    }
    cout << "? " << node.size();
    for(int x : node){
        cout << " " << x;
    }
    cout << endl;
    array<int, 2>ar{};
    cin >> ar[0] >> ar[1];
    return ar;
}

void solve() {
    int n;
    cin >> n;
    vector<vector<int>>col = {};
    vector<array<int, 2>>edge;

    auto div = [&](int r){

        vector<array<int, 2>>deg(r + 1);
        vector<vector<int>>G(r + 1);
        irep(i, 1, r)deg[i][1] = i;
        for(auto [u, v] : edge){
            deg[u][0] ++, deg[v][0] ++ ;
            G[u].emplace_back(v);
            G[v].emplace_back(u);
        }
        set<array<int, 2>>st;
        irep(i, 1, r)
            st.insert(deg[i]);
        vector<int>incol(r + 1, -1);
        function<void()> dfs = [&](){
            if(st.size() == 0)return;
            auto [Deg, u] = *st.begin();
            st.erase(st.begin());
            for(int v : G[u]){
                if(!st.contains(deg[v]))continue;
                st.erase(deg[v]);
                deg[v][0] --;
                st.insert(deg[v]);
            }
            dfs();
            vector<int>ban(col.size());
            for(int v : G[u]){
                if(incol[v] != -1)
                    ban[incol[v]] = 1;
            }
            for(int i = 0; i < col.size(); ++ i){
                if(ban[i] == 0){
                    incol[u] = i;
                    col[i].push_back(u);
                    break;
                }
            }
            if(incol[u] == -1){
                incol[u] = col.size();
                col.push_back({u});
            }
        };
        dfs();
    };
    irep(u, 1, n){
        col.clear();
        div(u - 1);

        int to = -1;
//        cerr << col.size() << endl;
        for(int c = 0; c < col.size(); ++ c){
            assert(c != col.size());
            auto vec = col[c];
            vec.push_back(u);
            auto [i, j] = query(vec);
            if(i == -1)to = c;

            while(i != -1){
                edge.push_back({i, j});
                vec.erase(find(vec.begin(), vec.end(), i + j - u));
                auto T = query(vec);
                i = T[0], j = T[1];
            }
        }
    }
    cout << "! " << edge.size() << endl;
    for(auto [u, v] : edge){
        cout << u << ' ' << v << endl;
    }
}

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