#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define eb emplace_back
#define mt make_tuple
using ll = long long;
using ii = pair<int, int>;
int M;
vector<int> U, V;
vector<int> gen_edges(vector<int> &in_grp) {
vector<int> ret(M, 0);
for (int i = 0; i < M; i++) {
ret[i] = (in_grp[U[i]] == in_grp[V[i]]);
}
return ret;
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
M = (int)U.size();
::U = U;
::V = V;
int s_xor_t = 0;
vector<int> init_grp;
for (int bit = 0; (1 << bit) < N; bit++) {
vector<int> in_grp(N, 0);
for (int i = 0; i < N; i++) {
in_grp[i] = !!(i & (1 << bit));
}
auto edges = gen_edges(in_grp);
if (ask(edges) % 2) {
// S and T are in different sets
init_grp = in_grp;
s_xor_t ^= (1 << bit);
}
}
assert(!init_grp.empty());
while (count(init_grp.begin(), init_grp.end(), 1) > 1) {
int cnt = count(init_grp.begin(), init_grp.end(), 1) / 2;
vector<int> new_init_grp(N, 0);
for (int i = 0; i < N; i++) {
if (init_grp[i] && cnt) {
cnt--;
new_init_grp[i] = 1;
} else {
new_init_grp[i] = 0;
}
}
auto edges = gen_edges(new_init_grp);
if (ask(edges) % 2 == 0) {
for (int i = 0; i < N; i++) {
new_init_grp[i] ^= init_grp[i];
}
}
init_grp = new_init_grp;
}
int S = find(init_grp.begin(), init_grp.end(), 1) - init_grp.begin(), T = S ^ s_xor_t;
answer(S, T);
}
