Tanssiaiset

#include <iostream>
#include <utility>

using namespace std;

#define N 100001
int p[N];
pair<int, int> inp[N];

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n; cin >> n; cin.ignore();
	int k = (n / 2) + 1;
	
	for (int i = 0; i < k; i++) {
		int a, b; cin >> a >> b; cin.ignore();
		p[a]++;
		p[b]++;
		inp[i] = make_pair(a, b);
	}
	
	for (int i = 0; i < k; i++) {
		pair<int,int> L = inp[i];
		int a = L.first,b=L.second;
		if ((p[a]==2)&&(p[b]==2)) {
			cout << a << " " << b;
			break;
		}
	}
	
	return 0;
}

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