#include "sequence.h"
#include<bits/stdc++.h>
// #include<atcoder/modint>
#define pb push_back
#define mp make_pair
#define rs resize
#define ft front()
#define bk back()
#define int long long
#define vi vector<int>
#define vvi vector<vector<int>>
#define pii pair<int, int>
#define vpii vector<pair<int, int>>
#define vc vector<char>
#define vb vector<bool>
#define mii map<int,int>
#define f0r(i,n) for(int i=0;i<n;i++)
#define FOR(i,k,n) for(int i=k;i<n;i++)
#define r0f(i,n) for(int i = n-1; i >= 0; i--)
#define R0F(i,k,n) for(int i = n-1; i >= k; i--)
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define in(a) int a; cin>>a
#define in2(a,b) int a,b; cin>>a>>b
#define in3(a,b,c) int a,b,c; cin>>a>>b>>c
#define in4(a,b,c,d) int a,b,c,d; cin>>a>>b>>c>>d
#define vin(v,n); vi v(n); f0r(i,n){cin>>v[i];}
#define out(a) cout<<a<<'\n'
#define out2(a,b) cout<<a<<' '<<b<<'\n'
#define out3(a,b,c) cout<<a<<' '<<b<<' '<<c<<'\n'
#define out4(a,b,c,d) cout<<a<<' '<<b<<' '<<c<<' '<<d<<'\n'
#define pout(a) cout<<a.first<<' '<<a.second<<'\n'
#define vout(v) for(auto u : v){cout<<u<<' ';} cout<<endl
#define dout(a) cout<<a<<' '<<#a<<endl
#define dout2(a,b) cout<<a<<' '<<#a<<' '<<b<<' '<<#b<<endl
#define yn(x); if(x){cout<<"YES"<<'\n';}else{cout<<"NO"<<'\n';}
#define p2(x) (1LL << (x))
#define pct(x) (__builtin_popcountll(x))
#define ist(x,y) ((x >> y) & 1)
template<class T, class U> bool ckmin(T& a, const U& b) { return (T)b < a ? a = (T)b, 1 : 0; }
template<class T, class U> bool ckmax(T& a, const U& b) { return a < (T)b ? a = (T)b, 1 : 0; }
const int leg = 1e9 + 7;
const int mod = 998244353;
using namespace std;
struct segtree{
vi mn, mx, lz, tl, tr; int n;
segtree(vi &a){
n = a.size(); mn.rs(4*n+5); mx.rs(4*n+5); lz.rs(4*n+5), tl.rs(4*n+5), tr.rs(4*n+5);
build(1, 0, n-1, a);
}
void pull(int v){
mx[v] = max(mx[v*2], mx[v*2+1]); mn[v] = min(mn[v*2], mn[v*2+1]);
}
void push(int v){
if(lz[v] == 0)return;
add(v*2, lz[v]); add(v*2+1, lz[v]);
lz[v] = 0;
}
void add(int v, int x){
lz[v] += x; mn[v] += x; mx[v] += x;
}
void build(int v, int l, int r, vi &a){
tl[v] = l; tr[v] = r;
if(l == r){
mn[v] = a[l], mx[v] = a[r]; return;
}
int mid = l + r >> 1;
build(v*2, l, mid, a); build(v*2+1, mid+1, r, a);
pull(v);
}
void update(int v, int l, int r, int x){
if(tl[v] > r || tr[v] < l)return;
if(tl[v] >= l && tr[v] <= r){add(v, x); return;}
push(v);
update(v*2, l, r, x); update(v*2+1, l, r, x);
pull(v);
}
int maxquer(int v, int l, int r){
if(tl[v] > r || tr[v] < l)return -4e18;
if(tl[v] >= l && tr[v] <= r){return mx[v];}
push(v);
return max(maxquer(v*2, l, r), maxquer(v*2+1, l, r));
}
int minquer(int v, int l, int r){
if(tl[v] > r || tr[v] < l)return 4e18;
if(tl[v] >= l && tr[v] <= r){return mn[v];}
push(v);
return min(minquer(v*2, l, r), minquer(v*2+1, l, r));
}
};
signed sequence(signed N, std::vector<signed> A) {
vvi w(N+1); f0r(i, N)w[A[i]].pb(i); vi tmp(N+1); FOR(i,1,N+1)tmp[i] = i; segtree S = segtree(tmp); signed ans = 1;
FOR(i,1,N+1){
int lo = 1; int hi = w[i].size();
while(lo < hi){
int mid = lo + (hi - lo + 1) / 2; bool ok = 0;
f0r(j, (int)w[i].size() - mid + 1){
// dout2(j, j + mid - 1);
int u = w[i][j];
int x = S.minquer(1, 0, u); int y = S.maxquer(1, 0, u);
if(S.minquer(1, w[i][j + mid - 1] + 1, N) <= 2 * mid + y && S.maxquer(1, w[i][j + mid - 1] + 1 , N) >= x){
ok = 1; break;
}
}
if(ok)lo = mid;
else hi = mid-1;
}
// dout(lo);
ckmax(ans, lo);
/*
for(auto &u : w[i]){
int x = S.minquer(1, 0, u); int y = S.maxquer(1, 0, u);
int lo = u; int hi = N-1;
while(lo < hi){
int mid = lo + (hi - lo + 1) / 2;
}
}
*/
/*
if(w[i].size() == 2){
int x = S.minquer(1, 0, w[i][0]); int y = S.maxquer(1, 0, w[i][0]);
// dout2(x,y);
if(S.minquer(1, w[i][1] + 1, N) <= 4 + y && S.maxquer(1, w[i][1] + 1, N) >= x)ans = 2;
}
*/
for(auto &u : w[i])S.update(1, u+1, N, -2);
}
return ans;
return 0;
}
