Gena loves sequences of numbers. Recently, he has discovered a new type of sequences which he called an almost arithmetical progression. A sequence is an almost arithmetical progression, if its elements can be represented as:

  * a1 = p, where p is some integer; 
  * ai = ai - 1 + ( - 1)i + 1·q (i > 1), where q is some integer. 



Right now Gena has a piece of paper with sequence b, consisting of n integers. Help Gena, find there the longest subsequence of integers that is an almost arithmetical progression.

Sequence s1, s2, ..., sk is a subsequence of sequence b1, b2, ..., bn, if there is such increasing sequence of indexes i1, i2, ..., ik (1 ≤ i1 < i2 < ... < ik ≤ n), that bij = sj. In other words, sequence s can be obtained from b by crossing out some elements.

Input

The first line contains integer n (1 ≤ n ≤ 4000). The next line contains n integers b1, b2, ..., bn (1 ≤ bi ≤ 106).

Output

Print a single integer — the length of the required longest subsequence.

Examples

Input

2
3 5


Output

2


Input

4
10 20 10 30


Output

3

Note

In the first test the sequence actually is the suitable subsequence. 

In the second test the following subsequence fits: 10, 20, 10.
import java.util.*;
import java.io.*;
import static java.lang.Math.*;

public class PracticeProblem
{
    /*
     * This FastReader code is taken from GeeksForGeeks.com
     * https://www.geeksforgeeks.org/fast-io-in-java-in-competitive-programming/
     *
     * The article was written by Rishabh Mahrsee
     */
    public static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException  e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }

    public static FastReader in = new FastReader();
    public static PrintWriter out = new PrintWriter(System.out);

    public static void main(String[] args)
    {
        int n = in.nextInt();

        int[] arr = new int[n];
        for (int i = 0; i < n; i++)
            arr[i] = in.nextInt();

        int[][] dp = new int[n][n];
        int[] dpStartingHere = new int[n];

        Map<Integer, Integer> map = new HashMap<>();

        Arrays.fill(dpStartingHere, 1);
        for (int i = 0; i < n; i++)
            Arrays.fill(dp[i], 1);

        int answer = 1;

        map.put(arr[n - 1], n - 1);

        for (int i = n - 2; i >= 0; i--)
        {
            for (int j = i + 1; j < n; j++)
            {
                dpStartingHere[i] = max(dpStartingHere[i], 1 + dp[j][i]);
            }
            answer = max(answer, dpStartingHere[i]);

            for (int prev = 0; prev < i; prev++)
                if (map.containsKey(arr[prev]))
                    dp[i][prev] = 1 + dp[map.get(arr[prev])][i];

            map.put(arr[i], i);
        }
        out.println(answer);
        out.close();
    }

}