#include <bits/stdc++.h>
#include "sequence.h"
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
struct Node{
int sum, pref, suff;
Node(int sum = 0, int pref = 0, int suff = 0) : sum(sum), pref(pref), suff(suff){}
};
struct SegmentTreeMax{
int n;
vector<Node> a;
Node combine(Node a, Node b){
return Node(a.sum + b.sum, max(a.pref, a.sum + b.pref), max(b.suff, b.sum + a.suff));
}
SegmentTreeMax(int _n){
n = _n;
a.resize(n * 2 + 2);
for(int i = 1; i<=n; ++i) a[i+n] = Node(-1, 0, 0);
for(int i = n; i >= 1; --i) a[i] = combine(a[i * 2], a[i * 2 + 1]);
}
void update(int i){
i += n; a[i] = Node(1, 1, 1);
while(i > 1){
i >>= 1;
a[i] = combine(a[i * 2], a[i * 2 + 1]);
}
}
Node get(int l, int r){
l += n; r += n + 1;
Node L(0, 0, 0), R(0, 0, 0);
while(l < r){
if (l & 1) L = combine(L, a[l++]);
if (r & 1) R = combine(a[--r], R);
l >>= 1; r >>= 1;
}
return combine(L, R);
}
};
struct SegmentTreeMin{
int n;
vector<Node> a;
Node combine(Node a, Node b){
return Node(a.sum + b.sum, min(a.pref, a.sum + b.pref), min(b.suff, b.sum + a.suff));
}
SegmentTreeMin(int _n){
n = _n;
a.resize(n * 2 + 2);
for(int i = 1; i<=n; ++i) a[i+n] = Node(-1, -1, -1);
for(int i = n; i >= 1; --i) a[i] = combine(a[i * 2], a[i * 2 + 1]);
}
void update(int i){
i += n; a[i] = Node(1, 0, 0);
while(i > 1){
i >>= 1;
a[i] = combine(a[i * 2], a[i * 2 + 1]);
}
}
Node get(int l, int r){
l += n; r += n + 1;
Node L(0, 0, 0), R(0, 0, 0);
while(l < r){
if (l & 1) L = combine(L, a[l++]);
if (r & 1) R = combine(a[--r], R);
l >>= 1; r >>= 1;
}
return combine(L, R);
}
};
const int N = 5e5 + 69;
vector<int> pos[N];
int sequence(int n, vector<int> a) {
for(int i = 0; i<n; ++i) pos[a[i]].push_back(i+1);
int ans = 0;
SegmentTreeMax st_max(n);
SegmentTreeMin st_min(n);
for(int i = 1; i<=n; ++i) if (pos[i].size()){
for(int j: pos[i]) st_max.update(j);
int l = 0;
for(int j = 0; j < pos[i].size(); ++j){
while(l <= j){
int cnt1 = st_min.get(pos[i][l], pos[i][j]).sum + st_min.get(1, pos[i][l]-1).suff + st_min.get(pos[i][j]+1, n).pref;
int cnt2 = st_max.get(pos[i][l], pos[i][j]).sum + st_max.get(1, pos[i][l]-1).suff + st_max.get(pos[i][j]+1, n).pref;
if (cnt1 < 1 && cnt2 >= 0) break;
l++;
}
maximize(ans, j - l + 1);
}
for(int j: pos[i]) st_min.update(j);
}
return ans;
}
// int main(){
// ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// clock_t start = clock();
// int n; cin >> n;
// vector<int> a(n);
// for(int i = 0; i<n; ++i) cin >> a[i];
// cout << sequence(n, a) << "\n";
// // SegmentTreeMin st_min(9);
// // cout << st_min.get(1, 2).suff << "\n";
// cerr << "Time elapsed: " << clock() - start << " ms\n";
// return 0;
// }
