#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <deque>
#include <set>
using namespace std;

int main(){
	int N;
	cin >> N;
	vector<int> A(N);
	for(int i=0; i<N; i++){
		cin >> A[i];
	}

	deque<int> dq;
	set<int> s;

	int ans = 0;
	for(int r=0; r<N; r++){
		auto itr = s.find( A[r] );
		if(itr != s.end()){
			while(dq.size() > 0){
				int val = dq.front();
				s.erase(val);
				dq.pop_front();
				if(val == A[r]) break;
			}
		}
		s.insert( A[r] );
		dq.push_back( A[r] );
		ans = max(ans, (int)dq.size());
	}

	cout << ans << endl;
	return 0;
}