//#include "grader.h"
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <vector>
#include <math.h>
#include <set>
//#define int long long
#define ff first
#define ss second
#define pb push_back
#define pp pop_back
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define r0 return 0
using namespace std;
const int N = 5 * 1e5 + 5, M = 55, MOD = 998244353;
int x,y,xx,yy,n,m,k,l,ans,tm;
vector <int> g[N],rd,v;
int fix[N],tc[N];
int kth(int i);
int cnt(int x);
void say_answer(int a);
void solve(int N){
n = N;
srand(time(0));
for (int i = 1; i <= 30; i++) {
int ind = rand() % n + 1;
v.pb(kth(ind));
}
int gambling = v[rand() % v.size()];
if (cnt(gambling) >= n / 3) say_answer(gambling);
else cout << -1 << endl;
}
