[1547] 공

#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
	bool v[4] = { false, true, false, false };
	int testcase, k = 0;
	cin >> testcase;
	for (int i = 1; i <= testcase; i++)
	{
		int a, b;
		cin >> a >> b;
		swap(v[a], v[b]);
	}
	for (int i = 1; i <= 3; i++)
	{
		if (v[i])
		{
			k = 1;
			cout << i;
			break;
		}
	}
	if (k == 0)
		cout << "-1";
}