#include <bits/stdc++.h>
using namespace std;
template<typename T>
int SIZE(T (&t)){
    return t.size();
}

template<typename T, size_t N>
int SIZE(T (&t)[N]){
    return N;
}

string to_string(char t){
    return "'" + string({t}) + "'";
}

string to_string(bool t){
    return t ? "true" : "false";
}

string to_string(const string &t, int x1=0, int x2=1e9){
    string ret = "";
    for(int i = min(x1,SIZE(t)), _i = min(x2,SIZE(t)-1); i <= _i; ++i){
        ret += t[i];
    }
    return '"' + ret + '"';
}

string to_string(const char* t){
    string ret(t);
    return to_string(ret);
}

template<size_t N>
string to_string(const bitset<N> &t, int x1=0, int x2=1e9){
    string ret = "";
    for(int i = min(x1,SIZE(t)); i <= min(x2,SIZE(t)-1); ++i){
        ret += t[i] + '0';
    }
    return to_string(ret);
}

template<typename T, typename... Coords>
string to_string(const T (&t), int x1=0, int x2=1e9, Coords... C);

template<typename T, typename S>
string to_string(const pair<T, S> &t){
    return "(" + to_string(t.first) + ", " + to_string(t.second) + ")";
}

template<typename T, typename... Coords>
string to_string(const T (&t), int x1, int x2, Coords... C){
    string ret = "[";
    x1 = min(x1, SIZE(t));
    auto e = begin(t);
    advance(e,x1);
    for(int i = x1, _i = min(x2,SIZE(t)-1); i <= _i; ++i){
        ret += to_string(*e, C...) + (i != _i ? ", " : "");
        e = next(e);
    }
    return ret + "]";
}

template<int Index, typename... Ts>
struct print_tuple{
    string operator() (const tuple<Ts...>& t) {
        string ret = print_tuple<Index - 1, Ts...>{}(t);
        ret += (Index ? ", " : "");
        return ret + to_string(get<Index>(t));
    }
};

template<typename... Ts>
struct print_tuple<0, Ts...> {
    string operator() (const tuple<Ts...>& t) {
        return to_string(get<0>(t));
    }
};

template<typename... Ts>
string to_string(const tuple<Ts...>& t) {
    const auto Size = tuple_size<tuple<Ts...>>::value;
    return print_tuple<Size - 1, Ts...>{}(t);
}

void dbgr(){;}
template<typename Heads, typename... Tails>
void dbgr(Heads H, Tails... T){
    cout << to_string(H) << " | ";
    dbgr(T...);
}

void dbgs(){;}
template<typename Heads, typename... Tails>
void dbgs(Heads H, Tails... T){
    cout << H << " ";
    dbgs(T...);
}

/*
formatted functions:
*/

/*
consider __VA_ARGS__ as a whole:
dbgv() prints values only
dbg() prints name and values
*/
#define dbgv(...) cout << to_string(__VA_ARGS__) << endl;

#define dbg(...) cout << "[" << #__VA_ARGS__ << "]: "; dbgv(__VA_ARGS__);
//#define dbg(...)

/*
consider __VA_ARGS__ as a sequence of arguments:
dbgr() prints values only
dbgm() prints names and values
*/
#define dbgr(...) dbgr(__VA_ARGS__); cout << endl;

#define dbgm(...) cout << "[" << #__VA_ARGS__ << "]: "; dbgr(__VA_ARGS__);

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

typedef long long ll;
typedef unsigned int ui;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pll;
// using u128 = __uint128_t;
// using i128 = __int128;
const int mod = 1000000007;
const int N = 2005;
const int LOG = 20;
const int inf = 1e9;
const double eps = 1e-11;
int n, m, qq;
vector<int> sets[N], adj[N];
int colour[N], deg[N], curdeg[N];
bitset<N> vis, colourvis;
pi query(vector<int> a) {
    cout << "? " << a.size() << " ";
    for (int x : a) cout << x << " ";
    cout << endl;
    int i, j;
    cin >> i >> j;
    return {i, j};   
}

void solve() {
    cin >> n;
    vector<pi> edges;
    for (int i = 2; i <= n; i++) {
        int addto = -1;
        priority_queue<pi, vector<pi>, greater<pi>> q;
        for (int j = 1; j < i; j++) {
            curdeg[j] = deg[j], colour[j] = -1, vis[j] = 0;
            q.push({deg[j], j});
        }
        
        vector<int> order;
        while (!q.empty()) {
            auto [d, u] = q.top();
            q.pop();
            if (d != curdeg[u]) continue;
            vis[u] = 1;
            order.push_back(u);
            for (int v : adj[u]) {
                curdeg[v]--;
                if (!vis[v]) q.push({curdeg[v], v});
            }
        }
        
        reverse(order.begin(), order.end());
        int mxx = 0;
        for (int u : order) {
            int mx = 0;
            for (int v : adj[u]) {
                int c = colour[v];
                if (c == -1) continue;
                colourvis[c] = 1, mx = max(mx, c);
            }
            
            int c = inf;
            for (int j = 0; j <= mx + 1; j++) {
                if (!colourvis[j]) {
                    c = min(c, j);
                }
                
                colourvis[j] = 0;
            }
            
            // dbgm(u, c, deg[u], curdeg[u]);
            mxx = max(mxx, c), colour[u] = c;
            sets[c].push_back(u);
        }
        
        for (int j = 0; j <= mxx; j++) {
            vector<int> s = sets[j];
            while (true) {
                vector<int> q = s;
                q.push_back(i);
                auto [u, v] = query(q);
                if (u == -1) {
                    break;
                }
                
                else {
                    edges.push_back({u, v});
                    adj[u].push_back(v);
                    adj[v].push_back(u);
                    deg[u]++, deg[v]++;
                    vector<int> ns;
                    for (int k = 0; k < s.size(); k++) {
                        if (s[k] != u && s[k] != v) {
                            ns.push_back(s[k]);
                        }
                    }
                    
                    s = ns;
                }
            }
        }
        
        for (int j = 0; j <= mxx; j++) {
            sets[j].clear();
        }
    }
    
    cout << "! " << edges.size() << "\n";
    for (auto [u, v] : edges) {
        cout << u << " " << v << "\n";
    }
}

int32_t main() {
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
}