#include "bits/stdc++.h"
using namespace std;
using ll = long long;
#define sz(v) ((int)v.size())
#define pb push_back
#ifdef ONPC
vector<int> p;
vector<int> ask(int x);
#else
#include "prize.h"
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int lv[1000];
int al[200005], ar[200005], a[200005];
void g(int x) {
if (a[x]) return;
a[x] = 1;
auto u = ask(x);
al[x] = u[0];
ar[x] = u[1];
lv[al[x]] = min(lv[al[x]], x);
}
int find_best(int n) {
for (int i = 0; i < 1000; ++i)
lv[i] = n+2;
vector<int> rs(n);
iota(rs.begin(), rs.end(), 0);
shuffle(rs.begin(), rs.end(), rng);
int cn = 0;
for (int i = 0; i < min(n,450); ++i) {
g(rs[i]);
cn = max(cn, al[rs[i]] + ar[rs[i]]);
}
vector<int> sp;
for (int i = 1; i <= cn; ++i) {
int l = (i > 1) ? sp.back()+1 : 0;
int r = n;
for (int j = i; j <= cn; ++j)
r = min(r, lv[j]);
while (l < r) {
int m = (l+r)/2;
g(m);
if (al[m] + ar[m] < cn || al[m] >= i)
r = m;
else
l = m+1;
}
sp.pb(l);
}
assert(sz(sp) == cn);
for (auto x : sp) {
g(x); if (al[x] == 0 && ar[x] == 0) return x;
}
return -1;
}
#ifdef ONPC
vector<int> ask(int x) {
vector<int> r(2,0);
for (int i = 0; i < x; ++i) if (p[i] < p[x]) ++r[0];
for (int i = x+1; i < sz(p); ++i) if (p[i] < p[x]) ++r[1];
return r;
}
int main() {
int n;
cin >>n; p.resize(n);
for (int i = 0; i < n; ++i)
cin >> p[i];
cout << find_best(n) << endl;
}
#endif
