#include "sequence.h"
#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
#define mp make_pair
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
int readint(){
int x=0,f=1; char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
const int N=5000500;
int n,a[N],val[N],pref[N];
vector<int> pos[N];
int sequence(int N,vector<int> A) {
n=N; for(int i=1;i<=n;i++) a[i]=A[i-1];
for(int i=1;i<=n;i++) pos[a[i]].pb(i);
//build(1,1,n);
for(int i=1;i<=n;i++) val[i]=1;
int ans=0;
for(int v=1;v<=n;v++){
if(pos[v].empty()) continue;
for(int j:pos[v]) val[j]=0;
// for(int j:pos[v]) modify(1,1,n,j,n,-1);
for(int i=1;i<=n;i++) pref[i]=pref[i-1]+val[i];
for(int l=1;l<=n;l++){
int cnt=0;
for(int r=l;r<=n;r++){
cnt+=(a[r]==v?1:0);
if(abs(pref[r]-pref[l-1])<=cnt) ans=max(ans,cnt);
}
}
// for(int j:pos[v]) modify(1,1,n,j,n,-1);
for(int j:pos[v]) val[j]=-1;
}
return ans;
}
