#include <iostream>
#include <fstream>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cassert>
#include <tuple>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
using namespace std;
typedef long long LL;
typedef vector<int> Vi;
typedef vector<LL> VL;
typedef vector<bool> Vb;
typedef vector<vector<int>> Vii;
#define forR(i, n) for (int i = 0; i < (n); i++)
Vi ask(int i);
int cntV = 0, N;
int getLeftNonVCnt(int i) {
int c = 0;
while (true) {
if (i >= N) return N - cntV;
Vi rs = ask(i);
if (rs[0] + rs[1] == N - cntV) {
// is a V node
return rs[0] - c;
} else {
i++;
c++;
}
}
}
int find_best(int n) {
N = n;
if (n <= 5000) {
forR(i, n) {
Vi rs = ask(i);
if (rs[0] == 0 && rs[1] == 0)
return i;
}
} else {
cntV = 0;
forR(i, 500) {
Vi rs = ask(i);
if (rs[0] == 0 && rs[1] == 0) return i;
cntV = max(cntV, n - rs[0] - rs[1]);
}
int cntNotV = n - cntV;
for (int t = 0; t < cntNotV; t++) {
// goal: get the t-th non-V node
int l = 0, r = n - 1;
while (l < r) {
int mid = (l + r) / 2;
if (getLeftNonVCnt(mid + 1) >= t) {
r = mid;
} else {
l = mid + 1;
}
}
// l is the t-th non-V node
Vi rs = ask(l); if (rs[0] == 0 && rs[1] == 0) return l;
}
return -1;
}
int l = 0, r = n - 1;
while (l < r) {
int mid = (l + r) / 2;
Vi rs = ask(mid);
if (rs[0] == rs[1]) return mid;
if (rs[0] == 1) {
r = mid - 1;
} else {
l = mid + 1;
}
}
return l;
}
#ifdef TEST_LOCAL
Vi _answer{ 2,2,1,2,2,2,2,2,2,2,2,2 };
Vi ask(int i) {
int n = _answer.size();
assert(i >= 0 && i < n);
int l = 0, r = 0;
for (int j = 0; j < n; j++) {
if (_answer[j] < _answer[i]) {
if (j < i) l++; else r++;
}
}
return Vi{ l, r };
}
int main() {
auto r = find_best(_answer.size());
return 0;
}
#endif
