Tanssiaiset

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n;
set<pair<ll,ll>> v;
set<ll> t;
int main() {
	cin >> n;
	vector<ll> loyt;
	for (int i=0; i<n; i++) {
		ll a,b;
		cin >> a >> b;
		v.insert({a,b});
		if (t.count(a) > 0) loyt.push_back(a);
		t.insert(a);
		if (t.count(b) > 0) loyt.push_back(b);
		t.insert(b);
	}
	if (v.count({loyt[0],loyt[1]}) > 0) cout << loyt[0] << " " << loyt[1] << "\n";
	else cout << loyt[1] << " " << loyt[0] << "\n";
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED