#include<bits/stdc++.h>
using namespace std;
int n,a[1000010],l,r,ans;
set<int> s;
int main(){
	cin>>n; l=r=1;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		if(s.count(a[i])){
			while(a[l]!=a[i]) s.erase(a[l++]);
			s.erase(a[l++]);
		}
		s.insert(a[i]);
		ans=max(ans,r-l+1);
		r++;
	}
	cout<<ans;
	return 0;
}