#include "sequence.h"
#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
#define pb push_back
#define ff first
#define ss second
int a[500100];
int s1[500100], s2[500100], c[500100];
struct node{
int x=1e9;
node *l = nullptr, *r = nullptr;
node(){}
};
node *t = new node();
void upd(node *v, int l, int r, int pos, int x){
if(l == r){
v -> x = min(v -> x, x);
return;
}
int mid = floor(((double)l + (double)r) / 2);
if(mid >= pos){
if(!v -> l) v->l = new node();
upd(v -> l, l, mid, pos, x);
}
else{
if(!v -> r) v->r = new node();
upd(v->r, mid+1, r, pos, x);
}
v -> x = 1e9;
if(v -> l) v -> x = min(v -> x, v -> l -> x);
if(v -> r) v -> x = min(v -> x, v -> r -> x);
}
int get(node *v, int l, int r, int L, int R){
if(r < L or R < l){
return 1e9;
}
if(L <= l and r <= R){
return v -> x;
}
int mid=floor(((double)l + (double)r) / 2);
int x = 1e9;
if(v -> l) x = min(x, get(v->l, l, mid, L, R));
if(v -> r) x = min(x, get(v->r, mid+1, r, L, R));
return x;
}
int sequence(int n, vector<int> A) {
int ans = 0;
for(int i=1; i<=n; i++){
a[i] = A[i - 1];
}
for(int x=1; x<=n; x++){
vector<pair<int, pii> > q;
for(int i=1; i<=n; i++){
if(a[i] == x) s1[i] = s1[i - 1] + 1, s2[i] = s2[i - 1] + 1, c[i] = c[i - 1] + 1;
if(a[i] > x) s1[i] = s1[i - 1] + 1, s2[i] = s2[i - 1] - 1, c[i] = c[i - 1];
if(a[i] < x) s1[i] = s1[i - 1] - 1, s2[i] = s2[i - 1] + 1, c[i] = c[i - 1];
q.pb({s1[i], {s2[i], i}});
}
t = new node();
q.pb({0, {0, 0}});
sort(q.begin(), q.end());
for(int i=0; i<q.size(); i++){
int x=q[i].ss.ff, pos=q[i].ss.ss;
upd(t, -n, n, x, pos);
int h = get(t, -n, n, -n, x);
if(h <= pos){
ans = max(ans, c[pos] - c[h]);
}
}
}
return ans;
}
