#include <bits/stdc++.h>
using namespace std;
//#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
struct node{
int s, e, m;
int mx, mn, lazy, val;
node *l, *r;
node(int _s, int _e){
s = _s, e = _e, m = (s + e) >> 1;
if(s != e)l = new node(s, m), r = new node(m+1, e);
mx = mn = lazy = val = 0;
}
void prop(){
if(!lazy)return;
mx += lazy, mn += lazy;
if(s != e)l->lazy += lazy, r->lazy += lazy;
lazy = 0;
}
void upd(int a, int b, int c){
if(a == s && b == e)lazy += c;
else{
if(b <= m)l->upd(a, b, c);
else if(a > m)r->upd(a, b, c);
else l->upd(a, m, c), r->upd(m+1, b, c);
l->prop(), r->prop();
mn= min(l->mn, r->mn);
mx= max(l->mx, r->mx);
}
}
pi qry(int a, int b){
prop();
if(a == s && b == e)return {mn, mx};
if(b <= m)return l->qry(a, b);
else if(a > m)return r->qry(a, b);
else{
pi lft = l->qry(a, m), rgt = r->qry(m+1 ,b);
return {min(lft.fi, rgt.fi), max(lft.se, rgt.se)};
}
}
int qm(int a, int b){
prop();
if(a == s && b == e)return mx;
if(b <= m)return l->qm(a, b);
if(a > m)return r->qm(a, b);
return max(l->qm(a, m), r->qm(m+1, b));
}
int qmm(int a, int b){
prop();
if(a == s && b == e)return mn;
if(b <= m)return l->qmm(a, b);
if(a > m)return r->qmm(a, b);
return min(l->qmm(a, m), r->qmm(m+1, b));
}
}*lft, *rgt, *lft2, *rgt2;
vector <int> occ[500005];
int sequence(int N, vector <int> A){
for(int i=0;i<N;i++)occ[A[i]].push_back(i);
lft = new node(0, N - 1);
rgt = new node(0, N - 1);
lft2 = new node(0, N - 1);
rgt2 = new node(0, N - 1);
int ans = 1;
for(int i=0;i<N;i++){
lft->upd(i, N - 1, 1);
rgt->upd(0, i, 1);
lft2->upd(i, N - 1, 1);
rgt2->upd(0, i, 1);
}
bool f = 0;
for(int i=1;i<=N;i++){
for(auto j : occ[i]){
lft2->upd(j, N - 1, -2);
rgt2->upd(0, j, -2);
}
int in = 0;
for(int j = 1; j < (int)occ[i].size(); j++){
int r = occ[i][j];
int tmp2 = lft->qm(r, N - 1), ref2 = lft->qm(r, r), tmp4 = lft2->qmm(r, N - 1), ref4 = lft2->qmm(r, r);
tmp2 -= ref2; tmp4 -= ref4;
while(in < j){
int l = occ[i][in];
int tmp = rgt->qm(0, l);
int ref = rgt->qm(l, l);
int tmp3 = rgt2->qmm(0, l);
int ref3 = rgt2->qmm(l, l);
tmp -= ref;
tmp += tmp2;
tmp3 -= ref3;
tmp3 += tmp4;
int val = ref2 - (l == 0 ? 0 : lft->qmm(l - 1, l - 1));
int val2 = ref4 - (l == 0 ? 0 : lft2->qmm(l - 1, l - 1));
long long mn = val + tmp, mx = val2 + tmp3;
if(mn * mx > 0)in++;
else break;
}
//cout << i << ' ' << j << ' ' << in << '\n';
ans = max(ans, j - in + 1);
}
for(auto j : occ[i]){
lft->upd(j, N - 1, -2);
rgt->upd(0, j, -2);
}
}
return ans;
}
