// Om Namah Shivaya
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a, b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a, b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
/*
refs:
https://codeforces.com/blog/entry/116491?#comment-1031309
edi
*/
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
#include "sequence.h"
template<typename T>
struct segtree {
// https://codeforces.com/blog/entry/18051
/*=======================================================*/
struct data {
int mnpref,mxpref,mnsuff,mxsuff,sum;
data(){
mnpref = mxpref = mnsuff = mxsuff = sum = 0;
}
};
data neutral = data();
data merge(data &left, data &right) {
data curr;
curr.mnpref = min(left.mnpref,left.sum+right.mnpref);
curr.mxpref = max(left.mxpref,left.sum+right.mxpref);
curr.mnsuff = min(right.mnsuff,right.sum+left.mnsuff);
curr.mxsuff = max(right.mxsuff,right.sum+left.mxsuff);
curr.sum = left.sum+right.sum;
return curr;
}
void create(int i, T v) {
tr[i].mnpref = tr[i].mnsuff = min(v,0);
tr[i].mxpref = tr[i].mxsuff = max(v,0);
tr[i].sum = v;
}
void modify(int i, T v) {
tr[i].mnpref = tr[i].mnsuff = min(v,0);
tr[i].mxpref = tr[i].mxsuff = max(v,0);
tr[i].sum = v;
}
/*=======================================================*/
int n;
vector<data> tr;
segtree() {
}
segtree(int siz) {
init(siz);
}
void init(int siz) {
n = siz;
tr.assign(2 * n, neutral);
}
void build(vector<T> &a, int siz) {
rep(i, siz) create(i + n, a[i]);
rev(i, n - 1, 1) tr[i] = merge(tr[i << 1], tr[i << 1 | 1]);
}
void pupd(int i, T v) {
modify(i + n, v);
for (i = (i + n) >> 1; i; i >>= 1) tr[i] = merge(tr[i << 1], tr[i << 1 | 1]);
}
data query(int l, int r) {
data resl = neutral, resr = neutral;
for (l += n, r += n; l <= r; l >>= 1, r >>= 1) {
if (l & 1) resl = merge(resl, tr[l++]);
if (!(r & 1)) resr = merge(tr[r--], resr);
}
return merge(resl, resr);
}
};
int sequence(int n, std::vector<int> a) {
a.insert(a.begin(),0);
vector<int> pos[n+5];
rep1(i,n) pos[a[i]].pb(i);
segtree<int> st(n+5);
rep1(i,n) st.pupd(i,1);
int ans = 0;
rep1(x,n){
auto &p = pos[x];
int siz = sz(p);
trav(i,p){
st.pupd(i,0);
}
int lo = 1, hi = siz;
while(lo <= hi){
int mid = (lo+hi) >> 1;
bool ok = false;
rep(i,siz){
if(i+mid-1 >= siz) break;
int l = p[i], r = p[i+mid-1];
int sum = st.query(l,r).sum;
if(abs(sum) <= mid){
ok = true;
break;
}
if(sum < 0){
int mxsuff = st.query(1,l-1).mxsuff;
int mxpref = st.query(r+1,n).mxpref;
sum += mxsuff+mxpref;
if(sum >= -mid){
ok = true;
}
}
else{
int mnsuff = st.query(1,l-1).mnsuff;
int mnpref = st.query(r+1,n).mnpref;
sum += mnsuff+mnpref;
if(sum <= mid){
ok = true;
}
}
if(ok){
break;
}
}
if(ok){
amax(ans,mid);
lo = mid+1;
}
else{
hi = mid-1;
}
}
trav(i,p){
st.pupd(i,-1);
}
}
return ans;
}
