#include "sequence.h"
#include <bits/stdc++.h>
#define pb push_back
#define fst first
#define snd second
#define fore(i,a,b) for(ll i=a,apio=b;i<apio;i++)
#define SZ(x) ((int)x.size())
#define ALL(x) x.begin(),x.end()
#define mset(a,v) memset((a),(v),sizeof(a))
#define imp(v) for(auto slkdh:v)cout<<slkdh<<" ";cout<<"\n"
using namespace std;
typedef int ll;
typedef pair<ll,ll> ii;
const ll C=5e5,MAXN=2*C+5;
#define NEUT 3*C
#define oper min
struct STree{
vector<ll>t; ll n;
STree(ll n):t(2*n+5,NEUT),n(n){}
void upd(ll p, ll v){
for(p+=n,t[p]=oper(t[p],v);p>1;p>>=1)t[p>>1]=oper(t[p],t[p^1]);
}
ll query(ll l, ll r){
ll res=NEUT;
for(l+=n,r+=n;l<r;l>>=1,r>>=1){
if(l&1)res=oper(res,t[l++]);
if(r&1)res=oper(res,t[--r]);
}
return res;
}
};
ll l[MAXN],r[MAXN];
bool cmp(ll i, ll j){
return ii({l[i],i})<ii({l[j],j});
}
int sequence(int N, std::vector<int> A) {
ll n=N;
vector<ll>a(n);
fore(i,0,n)a[i]=A[i]-1;
vector<ll>pos[n];
fore(i,0,n)pos[a[i]].pb(i);
vector<ll>s(n);
fore(i,0,n)s[i]=1;
ll res=0;
fore(i,0,n)if(SZ(pos[i])){
//cout<<"\nin"<<i<<":\n";
for(auto j:pos[i])s[j]=0;
//imp(s);
ll sum=0,rew=0;
vector<ll>rw(n+1);
vector<ll>ev{n};
l[n]=r[n]=rw[n]=0;
fore(j,0,n){
sum+=s[j],rew+=a[j]==i;
rw[j]=rew;
l[j]=sum-rew,r[j]=sum+rew;
ev.pb(j);
//cout<<j<<": "<<sum<<" "<<rew<<"\n";
//cout<<"add "<<p<<","<<q<<" "<<rew<<"\n";
//cout<<res<<"\n\n";
}
sort(ALL(ev),cmp); reverse(ALL(ev));
STree st(2*n+5+C);
for(auto i:ev){
/*if(i<0){
cout<<"-1\n";
st.upd(C,0);
continue;
}*/
//cout<<i<<": "<<l[i]<<","<<r[i]<<": "<<rw[i]<<" - "<<st.query(0,r[i]+C+1)<<" = "<<rw[i]-st.query(0,r[i]+C+1)<<"\n";
res=max(res,rw[i]-st.query(0,r[i]+C+1));
st.upd(r[i]+C,rw[i]);
}
//cout<<res<<"\n";
for(auto j:pos[i])s[j]=-1;
}
return res;
}
