#include <bits/stdc++.h>
void Solve(int N);
int Query(int x);
void Answer(int x, int y);
bool inMachine[100005];
int lastRes = 0;
void setInMachine(int i, bool val) {
if (inMachine[i] != val) {
lastRes = Query(i);
inMachine[i] = val;
}
}
int query() {
return lastRes;
}
int ans[50000];
std::vector<int> a, b;
void Solve(int N) {
for (int i = 1; i <= 2 * N; i++) {
int prev = query();
setInMachine(i, true);
if (prev != query()) {
a.push_back(i);
} else {
b.push_back(i);
}
}
/*std::cout << "Sets: " << std::endl;
std::cout << " ";
for (int x: a) std::cout << " " << x;
std::cout << std::endl;
std::cout << " ";
for (int x: b) std::cout << " " << x;
std::cout << std::endl;*/
for (int x: b) setInMachine(x, false);
int m = 1;
while (m < N) {
int cnt = 0;
for (int i = 0; i < N; i++) {
if (i & m) cnt++;
setInMachine(a[i], i & m);
}
for (int i = 0; i < N; i++) {
setInMachine(b[i], true);
if (query() == cnt) {
ans[i] += m;
}
setInMachine(b[i], false);
}
m <<= 1;
}
for (int i = 0; i < N; i++) {
Answer(b[i], a[ans[i]]);
}
}
#ifdef LOCAL_TEST
#include <cstdio>
#include <cstdlib>
#include <algorithm>
constexpr int MAX_N = 43000;
constexpr int MAX_CALLS = 1000000;
namespace {
void WrongAnswer(int code) {
printf("Wrong Answer [%d]\n", code);
exit(0);
}
int N;
int counterpart[2 * MAX_N + 1];
int num_queries;
int num_kinds;
int on[2 * MAX_N + 1];
int count[2 * MAX_N + 1];
int num_answers;
int answer[2 * MAX_N + 1];
} // namespace
int Query(int x) {
if (!(1 <= x && x <= 2 * N)) {
WrongAnswer(1);
}
if (++num_queries > MAX_CALLS) {
WrongAnswer(2);
}
const int type = std::min(x, counterpart[x]);
if (on[x]) {
--on[x];
--count[type];
if (count[type] == 0) {
--num_kinds;
}
} else {
++on[x];
++count[type];
if (count[type] == 1) {
++num_kinds;
}
}
return num_kinds;
}
void Answer(int a, int b) {
std::cout << "Answer(" << a << ", " << b << ")" << std::endl;
if (++num_answers > N) {
WrongAnswer(6);
}
if (!(1 <= a && a <= 2 * N && 1 <= b && b <= 2 * N)) {
WrongAnswer(3);
}
if (answer[a] != 0) {
WrongAnswer(4);
}
answer[a] = b;
if (answer[b] != 0) {
WrongAnswer(4);
}
answer[b] = a;
if (!(counterpart[a] == b && counterpart[b] == a)) {
WrongAnswer(5);
}
}
int secret_order[100000];
int main() {
if (scanf("%d", &N) != 1) {
fprintf(stderr, "Error while reading input\n");
exit(1);
}
for (int i = 0; i < 2 * N; ++i) {
secret_order[i] = i + 1;
}
std::mt19937 rng(0);
std::shuffle(secret_order, secret_order + 2 * N, rng);
for (int i = 1; i <= N; ++i) {
int x, y;
x = secret_order[2 * i - 2];
y = secret_order[2 * i - 1];
/*if (scanf("%d%d", &x, &y) != 2) {
fprintf(stderr, "Error while reading input\n");
exit(1);
}*/
printf("%d %d\n", x, y);
counterpart[x] = y;
counterpart[y] = x;
}
Solve(N);
if (num_answers != N) {
WrongAnswer(6);
}
printf("Accepted: %d\n", num_queries);
return 0;
}
#endif
