#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using ldb=long double;
using ull=unsigned long long;
const long long inf=0x3f3f3f3f3f3f3f3f;
using i128=__int128;
const int mod=1000000007;
const long double eps=0.00000000001;

ll a[1000010];
ll f[1000010];
ll dp0[1000010];
ll dp1[1000010];
map<ll,ll>b;
map<ll,ll>c0,c1;
void solve()
{
    ll n;
    cin>>n;
    ll mx0=0;
    ll mx1=0;
    for(ll i=1;i<=n;i++)cin>>a[i];
    for(ll i=n;i>=1;i--)
    {
        if(b.count(a[i]))f[i]=1;
        else f[i]=0;
        b[a[i]]++;
    }

    for(ll i=1;i<=n;i++)
    {
        if(f[i]==0)
        {
            if(c0.count(a[i])&&c1.count(a[i]))
            {
                dp0[i]=max(c0[a[i]],c1[a[i]])+1;
                c0[a[i]]=max(c0[a[i]],dp0[i]);
                c1[a[i]]=max(c1[a[i]],dp1[i]);
                mx0=max(mx0,dp0[i]);
            }
            else if(!c0.count(a[i])&&c1.count(a[i]))
            {
                dp0[i]=max(dp0[i],c1[a[i]]+1);
                c0[a[i]]=max(c0[a[i]],dp0[i]);
                c1[a[i]]=max(c1[a[i]],dp1[i]);
                mx0=max(mx0,dp0[i]);
            }
            else if(c0.count(a[i])&&!c1.count(a[i]))
            {
                dp0[i]=max(dp0[i],c0[a[i]]+1);
                c0[a[i]]=max(c0[a[i]],dp0[i]);
                c1[a[i]]=max(c1[a[i]],dp1[i]);
                mx0=max(mx0,dp0[i]);
            }
        }
        else if(f[i]==1)
        {
            //dp1[i]
            if(c0.count(a[i])&&c1.count(a[i]))
            {
                if(mx0==c0[a[i]]||mx0==c1[a[i]])
                {
                    dp0[i]=max(dp0[i],mx0+1);
                    dp1[i]=max(dp1[i],mx0+1);
                    c0[a[i]]=max(c0[a[i]],dp0[i]);
                    c1[a[i]]=max(c1[a[i]],dp1[i]);
                    mx0=max(mx0,dp0[i]);
                    mx1=max(mx1,dp1[i]);
                }
                else
                {
                    dp0[i]=max(c0[a[i]],c1[a[i]])+1;
                    dp1[i]=max(dp1[i],mx0+1);
                    c0[a[i]]=max(c0[a[i]],dp0[i]);
                    c1[a[i]]=max(c1[a[i]],dp1[i]);
                    mx0=max(mx0,dp0[i]);
                    mx1=max(mx1,dp1[i]);
                }
            }
            else if(!c0.count(a[i])&&c1.count(a[i]))
            {
                if(mx0==c1[a[i]])
                {
                    dp0[i]=max(dp0[i],mx0+1);
                    dp1[i]=max(dp1[i],mx0+1);
                    c0[a[i]]=max(c0[a[i]],dp0[i]);
                    c1[a[i]]=max(c1[a[i]],dp1[i]);
                    mx0=max(mx0,dp0[i]);
                    mx1=max(mx1,dp1[i]);
                }
                else
                {
                    dp0[i]=max(dp0[i],c1[a[i]]+1);
                    dp1[i]=max(dp1[i],mx0+1);
                    c0[a[i]]=max(c0[a[i]],dp0[i]);
                    c1[a[i]]=max(c1[a[i]],dp1[i]);
                    mx0=max(mx0,dp0[i]);
                    mx1=max(mx1,dp1[i]);
                }
            }
            else if(c0.count(a[i])&&!c1.count(a[i]))
            {
                if(mx0==c0[a[i]])
                {
                    dp0[i]=max(dp0[i],mx0+1);
                    dp1[i]=max(dp1[i],mx0+1);
                    c0[a[i]]=max(c0[a[i]],dp0[i]);
                    c1[a[i]]=max(c1[a[i]],dp1[i]);
                    mx0=max(mx0,dp0[i]);
                    mx1=max(mx1,dp1[i]);
                }
                else
                {
                    dp0[i]=max(dp0[i],c0[a[i]]+1);
                    dp1[i]=max(dp1[i],mx0+1);
                    c0[a[i]]=max(c0[a[i]],dp0[i]);
                    c1[a[i]]=max(c1[a[i]],dp1[i]);
                    mx0=max(mx0,dp0[i]);
                    mx1=max(mx1,dp1[i]);
                }
            }
            else if(!c0.count(a[i])&&!c1.count(a[i]))
            {
                dp1[i]=max(dp1[i],mx0+1);
                c1[a[i]]=max(c1[a[i]],dp1[i]);
                c0[a[i]]=max(c0[a[i]],dp0[i]);
                mx1=max(mx1,dp1[i]);
            }
            dp1[i]=max(dp1[i],1ll);
            mx1=max(mx1,dp1[i]);
        }
    }
    ll ans=0;
    
    printf("%lld\n",mx0);







    



}

int main()
{
    ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    ll _=1;
//    cin>>_;
    while(_--)
    {
        solve();
    }
    return 0;
}