#include<iostream>
#include<cstdio>
using namespace std;
int a[100005],b[100005];
int main(){
int n=0;
scanf("%d",&n);
for(int i=1;i<n+1;i++){
scanf("%d",&a[i]);
}
int l=1;
int r=0;
int ans=0;
while(l<=n&&r<n){
r++;
b[a[r]]++;
while(b[a[r]]>1){
b[a[l]]--;
l++;
}
ans=max(ans,r-l+1);
}
printf("%d",ans);
return 0;
}