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

int n,ecnt,go[4010],adj[2010],nxt[4010],d[2010],ld[2010],wo[2010],cnt[2010];
vector<int> op[2010];
vector<pair<int,int> > ed;

void add_(int u,int v) { go[++ecnt]=v, nxt[ecnt]=adj[u], adj[u]=ecnt, d[u]++;}
void query_(const vector<int> &q) {
    printf("? %d ",(int)q.size()), fflush(stdout);
    for (auto o : q) printf("%d ",o), fflush(stdout);
    printf("\n"), fflush(stdout);
}
pair<int,int> get_() {
    pair<int,int> ans; 
    scanf("%d%d",&ans.first,&ans.second), fflush(stdout);
    return ans;
}
void answer_(const vector<pair<int,int> > &ans) {
    printf("! %d\n",(int)ans.size()), fflush(stdout);
    for (auto o : ans) printf("%d %d\n",o.first,o.second), fflush(stdout);
}

int main() {
//    freopen("in.in","r",stdin);
//    freopen("out.out","w",stdout);

    scanf("%d",&n), fflush(stdout);

    for (int i=2;i<=n;i++) {
        set<pair<int,int> > s;
        for (int j=1;j<i;j++) s.insert(pair<int,int> (d[j],j)), ld[j]=d[j];
        vector<int> v;
        for (int j=1;j<i;j++) {
            int e=(*s.begin()).second; s.erase(s.begin());
            v.push_back(e), cnt[e]=1;
            for (int k=adj[e];k;k=nxt[k]) if (!cnt[go[k]]) ld[go[k]]--, s.erase(pair<int,int> (ld[go[k]]+1,go[k])), s.insert(pair<int,int> (ld[go[k]],go[k]));
        } 
        memset(cnt,0,sizeof(cnt));

        memset(wo,0,sizeof(wo));
        while (!v.empty()) {
            int e=v.back(); v.pop_back();
            for (int j=adj[e];j;j=nxt[j]) if (wo[go[j]]) cnt[wo[go[j]]]++;
            for (int j=1;j<=n;j++) if (!cnt[j]) { wo[e]=j, op[j].push_back(e); break;}
            for (int j=adj[e];j;j=nxt[j]) if (wo[go[j]]) cnt[wo[go[j]]]--;
        }
        
        for (int j=1;j<=n;j++) if (!op[j].empty()) while (1) {
            vector<int> q; q.push_back(i);
            for (auto o : op[j]) if (!cnt[o]) q.push_back(o);
            if (q.size()==1) break;
            query_(q);
            pair<int,int> ans=get_();
            if (ans.first==-1) break;
            if (ans.first==i) swap(ans.first,ans.second);
            add_(ans.first,ans.second), add_(ans.second,ans.first), ed.push_back(ans), cnt[ans.first]=1;
        }

        memset(cnt,0,sizeof(cnt));
        for (int j=1;j<=n;j++) if (!op[j].empty()) op[j].clear();
    }

    answer_(ed);

    return 0;
}