Tanssiaiset

#include <iostream>
#include <cmath>
#include <iomanip>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
    unsigned long long n;

    cin >> n;


    vector<unsigned long long> inputs;

    for(unsigned long long i = 0; i < n/2 + 1; i++)
    {
        unsigned long long a = 0;
        cin >> a;
        inputs.push_back(a);
        cin >> a;
        inputs.push_back(a);
    }
    bool f1 = false, f2 = false;
    for(unsigned long long i = n/2 + 1; i >= i; i--){
        for(unsigned long long o = n/2 + 1; o >= 0; o--){
            if(o != i){
                if(inputs[o * 2] == inputs[i * 2])
                {
                    f1 = true;
                }
                else if(inputs[o * 2 + 1] == inputs[i * 2])
                {
                    f1 = true;
                }
                else if(inputs[o * 2] == inputs[i * 2 + 1])
                {
                    f2 = true;
                }
                else if(inputs[o * 2 + 1] == inputs[i * 2 + 1])
                {
                    f2 = true;
                }
                if(f1 == true && f2 == true)
                {
                    cout << inputs[i * 2] << " " << inputs[i * 2 + 1] << "\n";
                    return 0;
                }
            }
        }
    }

    return 0;
}

Test 1

Group: 1

Verdict: RUNTIME ERROR

Test 2

Group: 1

Verdict: RUNTIME ERROR

Test 3

Group: 1

Verdict: RUNTIME ERROR

Test 4

Group: 1

Verdict: RUNTIME ERROR

Test 5

Group: 1

Verdict: RUNTIME ERROR

Test 6

Group: 2

Verdict: RUNTIME ERROR

Test 7

Group: 2

Verdict: RUNTIME ERROR

Test 8

Group: 2

Verdict: RUNTIME ERROR

Test 9

Group: 2

Verdict: RUNTIME ERROR

Test 10

Group: 2

Verdict: RUNTIME ERROR