//
// 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;

UINT hashtable;


SLL hashTable[1000005];

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

	SLL a[100005];
	

	cin >> N;
	v.resize(N + 1);

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

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

	SLL L, R, ans=0, max_ans = 0,max_ans2 = 0;


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


	//Nが2以上のとき
	const int search_complete = 1;
	const int search_break = 0;
	int flag;
	SLL i;

	L = 0;
	R = L;

	flag = search_complete;

	do {
		   
			if (hashTable[a[R]] == 0)
			{
				//バケット配列にインデックスをいれる(インデックス0と何もないの0を区別するために1から始める)
				hashTable[a[R]] = R+1;

				if (max_ans < R - L + 1 )
					max_ans = R - L + 1;
			}
			else
			{
				
				flag = search_break;
			}


		//cout << "L=" << L << ",R=" << R << ",ans=" << max_ans << endl;

		if (flag == search_break)
		{
			ans = 0;

			if(L < hashTable[a[R]])
				L = hashTable[a[R]]; //予め+1しているのでそのまま入れる

			hashTable[a[R]] = R+1;
			
			flag = search_complete;
		}

		R++;

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

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

	return 0; //end
}