#include <algorithm>
#include <random>
#include <vector>
int Query(int x);
void Answer(int x, int y);
void Solve(int n) {
int pr = Query(1);
std::vector<int> set1 = {1}, set2;
for (int i = 2; i <= 2 * n; ++i) {
int ne = Query(i);
(pr == ne ? set2 : set1).push_back(i);
pr = ne;
}
std::random_device rd;
std::mt19937 rng(rd());
std::shuffle(set2.begin(), set2.end(), rng);
auto solve = [&](auto &&self, int l, int r, bool added) {
if (l == r) {
Answer(set1[l], set2[l]);
return;
}
int m = l + (r - l) * 0.38;
for (int i = l; i <= m; ++i) {
pr = Query(set1[i]);
}
int trues = 0, falses = 0;
std::partition(set2.begin() + l, set2.begin() + r + 1, [&](int x) {
if (falses >= r - m) {
return true;
}
if (trues >= m - l + 1) {
return false;
}
int ne = Query(x);
bool cond = (pr == ne) ^ added;
pr = ne;
trues += cond, falses += !cond;
return cond;
});
self(self, l, m, !added);
self(self, m + 1, r, added);
};
solve(solve, 0, n - 1, true);
}
