//
// Yukicoder
// No.3009


//#include "stdafx.h"
#include <stdio.h>
#include <iostream>
#include <vector>
#include <list>//list
#include <set> //tree
#include <map> //連想配列
#include <unordered_set> //hash
#include <unordered_map> //hash
#include <algorithm>
#include <iomanip>
#include <string>
#include <stdlib.h>


using namespace std;
typedef unsigned long long ULL;
typedef signed long long SLL;
typedef unsigned int UINT;


#define START (0)
#define RIGHT (1)
#define UP    (2)
#define LEFT  (3)
#define DOWN  (4)

#define DATA_MAX (1000000)
#define FMAX(a,b)  ((a)>(b)?(a):(b))
#define FMIN(a,b)  ((a)<(b)?(a):(b))


vector <vector <SLL>> memo2;//二次元可変配列

vector<SLL> memo1;
vector<SLL> c;
vector<SLL> v;
vector<SLL> dp;

SLL H ,A, B, T, F, N, M, Result;


SLL backet[1000005];

int main(int argc, char *argv[])
{

	SLL a[100005];
	

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

	//cout << "-----" << endl;

	SLL L, R, ans=0, max_ans = 0;

	for (int i = 0; i < 1000005; i++)
	{
		backet[i] = -1;
	}


	//Nが1以下のとき
	if (N <= 1)
	{
		cout << N << endl;
		return 0;
	}

	//Nが2以上のとき
	L = 0;
	R = 0;

	do {
			
			//今回の数値が過去の数列に含まれていたら....
			if (backet[a[R]] != -1)
			{			
				// 左側の位置を更新
				if (L <= backet[a[R]])
					L = backet[a[R]]+1;				
			}

			//バケット配列に配列インデックスをいれる
			backet[a[R]] = R;

			if (max_ans < R - L + 1)
				max_ans = R - L + 1;

		//cout << "L=" << L << ",R=" << R << ",ans=" << max_ans << ",backet[a[R]]=" << backet[a[R]] << ",a[R]=" << a[R] << endl;

		//右側は毎回更新
		R++;

	} while (R < N);
	
	cout << max_ans << endl;

	///////////////////
	//cout << endl;
	//getchar();

	return 0; //end
}