#include <iostream>
#include <set>
#include <queue>
using namespace std;
int main(){
    int n;cin>>n;
    set<int> A;
    queue<int> B;
    int ans = 0;
    for(int i = 0; n > i; i++){
        int x;cin>>x;
        if(A.count(x)){
            while(B.front() != x){
                A.erase(B.front());
                B.pop();
            }
            B.pop();
            
        }
        B.push(x);
        A.insert(x);
        ans = max(ans,(int)B.size());
    }
    cout << ans << endl;
}