#ifdef EVAL
#include "grader.h"
#endif
#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
#ifndef EVAL
void solve(int N);
int kth(int i) {
int x;
cout << "v[" << i << "]: ";
cin >> x;
return x;
}
int cnt(int x) {
int ans;
cout << "cnt(" << x << "): ";
cin >> ans;
return ans;
}
void say_answer(int a) {
cout << "ans: " << a << '\n';
}
int main() {
int n;
cin >> n;
solve(n);
}
#endif
void solve(int n)
{
mt19937_64 rd(time(0));
Loop (_,0,30) {
int p = rd()%n;
int v = kth(p+1);
int c = cnt(v);
if (c*3 > n) {
say_answer(v);
return;
}
}
say_answer(-1);
}
