#include "sequence.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define P pair
#define F first
#define all(v) v.begin(),v.end()
#define V vector
#define pb push_back
#define S second
const ll MOD=(ll)1e9+7;
struct segtree{
private:
struct node{
int mind;
int maxd;
};
node single(int v){
return {v,v};
}
node neutral={INT_MAX,INT_MIN};
node merge(node a,node b){
return {min(a.mind,b.mind),max(a.maxd,b.maxd)};
}
node modification(node a,int v){
return {a.mind+v,a.maxd+v};
}
int operation_modifier(int a,int v){
return a+v;
}
public:
int size;
V<node>query;
V<int>operation;
void init(int n){
size=1;
while(size<n)size*=2;
query.assign(2*size,neutral);
operation.assign(2 * size, 0);
}
void build(V<int>&a,int x,int lx,int rx){
if(rx-lx==1){
if(lx<(int)a.size()){
query[x]=single(a[lx]);
}
return;
}
int m=(lx+rx)/2;
build(a,2*x+1,lx,m);
build(a,2*x+2,m,rx);
query[x]=merge(query[2*x+1],query[2*x+2]);
}
void build(V<int>&a){
build(a,0,0,size);
}
void set(int l,int r,int v,int x,int lx,int rx){
if(lx>=r || rx<=l){
return;
}
if(l<=lx && rx<=r){
query[x]=modification(query[x],v);
operation[x]= operation_modifier(operation[x],v);
return;
}
int m=(lx+rx)/2;
set(l,r,v,2*x+1,lx,m);
set(l,r,v,2*x+2,m,rx);
query[x]=modification(merge(query[2*x+1],query[2*x+2]),operation[x]);
}
void set(int l,int r,int v){
set(l,r,v,0,0,size);
}
node calc(int l,int r,int x,int lx,int rx){
if(rx<=l || lx>=r){
return neutral;
}
if(l<=lx && rx<=r)
return query[x];
int m=(lx+rx)/2;
node a=calc(l,r,2*x+1,lx,m);
node b=calc(l,r,2*x+2,m,rx);
return modification(merge(a,b),operation[x]);
}
int mind(int l,int r){
return calc(l,r,0,0,size).mind;
}
int maxd(int l,int r){
return calc(l,r,0,0,size).maxd;
}
};
bool inter(P<int,int>a,P<int,int>b){
if(a.F>b.F)
swap(a,b);
return a.S>=b.F;
}
int sequence(int N,V<int>A){
V<int>a(N+1);
V<int>occ(N+1);
V<V<int>>pos(N+1);
set<int>st;
for(int i=1;i<=N;i++) {
a[i] = A[i - 1];
occ[a[i]]++;
pos[a[i]].pb(i);
st.insert(a[i]);
}
V<int>d;
for(auto u:st)
d.pb(u);
V<int>b=a;
sort(all(b));
int ans=max(occ[b[(N+1)/2]],occ[b[(N+2)/2]]);
V<int>vp(N+1);
vp[0]=0;
for(int i=1;i<=N;i++){
vp[i]=vp[i-1]+1;
}
segtree tree;
tree.init(N);
tree.build(vp);
for(auto u:d){
V<P<P<int,int>,P<int,int>>>q;
int sz=(int)pos[u].size();
for(int i=0;i<sz;i++){
int mnl=tree.mind(0,pos[u][i]+1);
int mxl=tree.maxd(0,pos[u][i]+1);
int mnr=tree.mind(pos[u][i],N+1);
int mxr=tree.maxd(pos[u][i],N+1);
q.pb({{mnl,mxl},{mnr,mxr}});
}
int l=1,r=N;
while(l<=r){
int m=l+(r-l)/2;
bool flag=false;
for(int i=0;i+m-1<sz;i++){
P<int,int>p1={q[i].F.F,q[i].F.S};
P<int,int>p2={q[i+m-1].S.F,q[i+m-1].S.S};
if(inter(p1,p2))
flag=true;
}
if(flag){
ans=max(ans,m);
l=m+1;
}
else
r=m-1;
}
for(int i=0;i<sz;i++){
tree.set(pos[u][i],N+1,-2);
}
q.clear();
for(int i=0;i<sz;i++){
int mnl=tree.mind(0,pos[u][i]+1);
int mxl=tree.maxd(0,pos[u][i]+1);
int mnr=tree.mind(pos[u][i],N+1);
int mxr=tree.maxd(pos[u][i],N+1);
q.pb({{mnl,mxl},{mnr,mxr}});
}
l=1,r=N;
while(l<=r){
int m=l+(r-l)/2;
bool flag=false;
for(int i=0;i+m-1<sz;i++){
P<int,int>p1={q[i].F.F,q[i].F.S};
P<int,int>p2={q[i+m-1].S.F,q[i+m-1].S.S};
if(inter(p1,p2))
flag=true;
}
if(flag){
ans=max(ans,m);
l=m+1;
}
else
r=m-1;
}
}
return ans;
}
