#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ull mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
//mt19937_64 rng(1);
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double wow = (double) ((ull) rng()) / ((ull)(0-1));
return wow * (r - l) + l;
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
#include "minerals.h"
void Solve(int N);
namespace InteractorLib{
vector<int> color;
vector<bool> chosen;
map<int, int> mp;
vector<pair<int, int>> ans;
int o_cnt = 0;
int Query(int i){
o_cnt++;
if (!chosen[i]){
mp[color[i]]++;
}
else{
mp[color[i]]--;
if (mp[color[i]] == 0) mp.erase(color[i]);
}
chosen[i] = !chosen[i];
return mp.size();
}
void Answer(int i, int j){
if (i > j) swap(i, j);
ans.push_back({i, j});
}
int grade(){
int n = 42000;
// int n; cin >> n;
color.resize(n * 2 + 1); chosen.resize(n * 2 + 1);
// for(int i = 1; i <= n*2; ++i) cin >> color[i];
for(int i = 1; i<= n*2; ++i) color[i] = (i + 1) / 2;
shuffle(1 + ALL(color), rng);
o_cnt = 0;
mp.clear();
ans.clear();
Solve(n);
cout << "Operation used: " << o_cnt << "\n";
remove_dup(ans);
if (ans.size() != n) return 0;
for(pair<int, int> i: ans)
if (i.first == i.second || color[i.first] != color[i.second])
return 0;
return 1;
}
}
pair<int, int> P;
vector<int> rape_victim;
void dnc(vector<int> &X, vector<int> Y, vector<int> &ans, int l, int r){
if (l == r){
ans[Y[0]] = X[l];
return;
}
int mid = (l+r)>>1;
int cnt = 0;
if (P == make_pair(l, r)){
for(int i = mid + 1; i <= r; ++i)
cnt = Query(X[i]);
}
else{
for(int i = l; i <= mid; ++i)
cnt = Query(X[i]);
}
P = {l, mid};
vector<int> left, right;
for(int i: Y){
if (rape_victim[i] <= mid) {
left.push_back(i);
continue;
}
if (left.size() == mid - l + 1) {
right.push_back(i);
continue;
}
if (right.size() == r - mid){
left.push_back(i);
continue;
}
int _cnt = Query(i);
if (_cnt == cnt) left.push_back(i);
else right.push_back(i);
cnt = _cnt;
}
dnc(X, left, ans, l, mid);
dnc(X, right, ans, mid+1, r);
}
void Solve(int n) {
vector<int> perm(n*2+1);
for(int i = 1; i <= n*2; ++i) perm[i] = i;
rape_victim.resize(n * 2 + 1);
shuffle(1 + ALL(perm), rng);
vector<int> X, Y;
for(int it = 1; it <= n * 2; ++it){
int i = perm[it];
X.push_back(i);
if (Query(i) != X.size()){
X.pop_back();
Y.push_back(i);
rape_victim[i] = X.size();
}
}
P = {0, n-1};
vector<int> ans(n*2+1, -1);
dnc(X, Y, ans, 0, n-1);
for(int i = 1; i <= n*2; ++i) if (ans[i] != -1) Answer(i, ans[i]);
}
