#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M = U.size(), lo, hi;
ll s = ask(vector<int>(M));
vector<vector<pair<int, int>>> adj(N);
for (int i = 0; i < M; i++) {
adj[U[i]].emplace_back(V[i], i);
adj[V[i]].emplace_back(U[i], i);
}
vector<int> W(M);
lo = 0, hi = M - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
auto w = W;
for (int i = 0; i <= mi; i++) {
w[i] = 1;
}
if (ask(w) == s) {
W = w;
lo = mi + 1;
} else {
hi = mi;
}
}
auto bfs = [&](int s) {
vector<int> dis(N, -1), f(N, -1);
dis[s] = 0;
queue<int> q;
q.push(s);
while (!q.empty()) {
int x = q.front();
q.pop();
for (auto [y, z] : adj[x]) {
if (dis[y] == -1 && !W[z]) {
dis[y] = dis[x] + 1;
f[y] = z;
q.push(y);
}
}
}
return make_pair(dis, f);
};
int P = U[lo], Q = V[lo];
auto [d0, f0] = bfs(P);
auto [d1, f1] = bfs(Q);
f0[P] = lo;
f1[Q] = lo;
vector<int> w(M, 1);
vector<bool> vis(N);
vis[P] = 1;
for (int i = 0; i < N; i++) {
if (d0[i] < d1[i] && d0[i] != -1) {
int x = i;
while (!vis[x]) {
vis[x] = 1;
w[f0[x]] = 0;
x ^= U[f0[x]] ^ V[f0[x]];
}
}
}
int t = (s + (s / A) * (B - A) - ask(w)) / (B - A);
vector<int> cand;
for (int i = 0; i < N; i++) {
if (d0[i] == t && d0[i] < d1[i] && d0[i] != -1) {
cand.push_back(i);
}
}
lo = 0, hi = cand.size() - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
vector<int> w(M);
for (int i = 0; i <= mi; i++) {
w[f0[cand[i]]] = 1;
}
if (ask(w) == s + B - A) {
hi = mi;
} else {
lo = mi + 1;
}
}
int S = cand[lo];
cand.clear();
for (int i = 0; i < N; i++) {
if (d1[i] == s / A - t - 1 && d1[i] < d0[i] && d1[i] != -1) {
cand.push_back(i);
}
}
lo = 0, hi = cand.size() - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
vector<int> w(M);
for (int i = 0; i <= mi; i++) {
w[f1[cand[i]]] = 1;
}
if (ask(w) == s + B - A) {
hi = mi;
} else {
lo = mi + 1;
}
}
answer(S, cand[lo]);
}
