#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace __gnu_pbds;
using namespace std;
#include "chameleon.h"
template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
set<pair<int, int>> Sa;
void Ans(int x, int y) {
if(x>y) swap(x,y);
if(x==y) return;
Sa.insert({x,y});
}
void Finish() {
for(auto[a,b] : Sa) Answer(a,b);
}
vector<int> get_vec(set<int> s, int a, int b) {
int idx = 0;
vector<int> ans;
for(auto x : s) {
if(a<=idx && idx <= b)ans.push_back(x);
idx++;
}
return ans;
}
void Solve(int N) {
vector<set<int>> V(2*N+1);
vector<vector<int>> G(2*N+1);
vector<set<int>> sets(2);
vector<int> is_sure(2*N+1);
for(int i=1; i<=2*N; ++i) {
int put = -1;
for(int k=0; k<3; ++k) {
vector<int> q = get_vec(sets[k], 0, sets[k].size()-1);
q.push_back(i);
int Q = Query(q);
if(q.size()==Q) put = k;
int start = 0;
while(q.size() - Q > 0) {
int lo = 0;
int hi = sets[k].size() - 1;
while(lo < hi) {
int mid=(lo+hi)/2;
vector<int> p = get_vec(sets[k], start, mid); p.push_back(i);
if(p.size() - Query(p) > 0) hi = mid;
else lo = mid+1;
}
vector<int> doc = get_vec(sets[k], lo, lo);
G[i].push_back(doc[0]);
G[doc[0]].push_back(i);
start = lo+1;
q = get_vec(sets[k], start, sets[k].size()-1);
q.push_back(i);
Q = Query(q);
}
}
if(i<=N) put = 0;
else put=1;
sets[put].insert(i);
}
for(int i=1; i<=2*N; ++i) for(auto x : G[i]) V[i].insert(x);
for(int i=1; i<=2*N; ++i) {
if(V[i].size()==1) Ans(i,*V[i].begin());
else {
vector<int> v;
for(auto x : G[i]) v.push_back(x);
for(int j=0; j<3; ++j) {
vector<int> p = {i};
for(int x=0; x<3; ++x) if(x!=j) p.push_back(v[x]);
if(Query(p)==1) {
V[i].erase(v[j]);
V[v[j]].erase(i);
}
}
}
}
for(int i=1; i<=2*N; ++i) {
if(V[i].size()==1) Ans(i,*V[i].begin());
}
Finish();
}
