#include<bits/stdc++.h>
using namespace std;
#define io ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
main()
{
io
int n;
cin>>n;
unordered_map<int,int>lastind;
int a[n+1];
for(int i=1;i<=n;i++)
{
cin>>a[i];
}
int i=1,ans=0;
for(int j=1;j<=n;j++)
{
i=max(i,lastind[a[j]]+1);
ans=max(ans,j-i+1);
lastind[a[j]]=j;
}
cout<<ans<<endl;
}
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