#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <array>
#include <string>
#include <algorithm>
#include <cmath>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <utility>
#include <random>
#include <cassert>
#include <fstream>
#include "sequence.h"
using namespace std;
mt19937 rnd(7069);
typedef int itn;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef float fl;
typedef long double ld;
using vi = vector<int>;
using vll = vector<ll>;
using mii = map<int, int>;
using mll = map<ll, ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define ff first
#define ss second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define mpr make_pair
#define yes cout<<"Yes\n"
#define no cout<<"No\n"
#define all(x) (x).begin(), (x).end()
const int MAX = int(2e9 + 5);
const ll MAXL = ll(1e18) + 5ll;
const int N = 500005;
int a[N], f[N];
int n;
void add_fen(int ind, int val) {
while (ind <= n) {
f[ind] += val;
ind += (ind & -ind);
}
}
int sum_fen(int ind) {
int ret = 0;
while (ind) {
ret += f[ind];
ind -= (ind & -ind);
}
return ret;
}
int qry_fen(int l, int r) {
return sum_fen(r) - sum_fen(l - 1);
}
int sol1() {
int len;
int ret = 0;
vi cnt(n + 1);
for (int i = 1; i <= n; ++i) {
cnt.assign(n + 1, 0);
for (int j = 1; j <= n; ++j) add_fen(j, -qry_fen(j, j));
len = 0;
for (int j = i; j <= n; ++j) {
++cnt[a[j]];
add_fen(a[j], 1);
++len;
int ind1, ind2;
if (len % 2) {
ind1 = ind2 = len / 2 + 1;
}
else {
ind1 = len / 2;
ind2 = len / 2 + len % 2;
}
int l = 1, r = n, mid;
while (l <= r) {
mid = (l + r) / 2;
int index = qry_fen(1, mid);
int cnt_x = cnt[mid];
if (index - cnt_x >= ind1) {
r = mid - 1;
}
else if (index < ind1) {
l = mid + 1;
}
else if (cnt_x) {
ret = max(ret, cnt_x);
break;
}
else {
r = mid - 1;
}
}
while (l <= r) {
mid = (l + r) / 2;
int index = qry_fen(1, mid);
int cnt_x = cnt[mid];
if (index - cnt_x >= ind2) {
r = mid - 1;
}
else if (index < ind2) {
l = mid + 1;
}
else if (cnt_x) {
ret = max(ret, cnt_x);
break;
}
else {
r = mid - 1;
}
}
}
}
return ret;
}
int sequence(int N, std::vector<int> A) {
n = N;
for (int i = 1; i <= n; ++i) {
a[i] = A[i - 1];
}
return sol1();
}
/*
7
1 2 3 1 2 1 3
3
9
1 1 2 3 4 3 2 1 1
2
14
2 6 2 5 3 4 2 1 4 3 5 6 3 2
3
*/
