Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests.
If you've seen these problems, a virtual contest is not for you - solve these problems in the archive.
If you just want to solve some problem from a contest, a virtual contest is not for you - solve this problem in the archive.
Never use someone else's code, read the tutorials or communicate with other person during a virtual contest.

No tag edit access

The problem statement has recently been changed. View the changes.

×
C. Mr. Kitayuta, the Treasure Hunter

time limit per test

1 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputThe Shuseki Islands are an archipelago of 30001 small islands in the Yutampo Sea. The islands are evenly spaced along a line, numbered from 0 to 30000 from the west to the east. These islands are known to contain many treasures. There are *n* gems in the Shuseki Islands in total, and the *i*-th gem is located on island *p*_{i}.

Mr. Kitayuta has just arrived at island 0. With his great jumping ability, he will repeatedly perform jumps between islands to the east according to the following process:

- First, he will jump from island 0 to island
*d*. - After that, he will continue jumping according to the following rule. Let
*l*be the length of the previous jump, that is, if his previous jump was from island*prev*to island*cur*, let*l*=*cur*-*prev*. He will perform a jump of length*l*- 1,*l*or*l*+ 1 to the east. That is, he will jump to island (*cur*+*l*- 1), (*cur*+*l*) or (*cur*+*l*+ 1) (if they exist). The length of a jump must be positive, that is, he cannot perform a jump of length 0 when*l*= 1. If there is no valid destination, he will stop jumping.

Mr. Kitayuta will collect the gems on the islands visited during the process. Find the maximum number of gems that he can collect.

Input

The first line of the input contains two space-separated integers *n* and *d* (1 ≤ *n*, *d* ≤ 30000), denoting the number of the gems in the Shuseki Islands and the length of the Mr. Kitayuta's first jump, respectively.

The next *n* lines describe the location of the gems. The *i*-th of them (1 ≤ *i* ≤ *n*) contains a integer *p*_{i} (*d* ≤ *p*_{1} ≤ *p*_{2} ≤ ... ≤ *p*_{n} ≤ 30000), denoting the number of the island that contains the *i*-th gem.

Output

Print the maximum number of gems that Mr. Kitayuta can collect.

Examples

Input

4 10

10

21

27

27

Output

3

Input

8 8

9

19

28

36

45

55

66

78

Output

6

Input

13 7

8

8

9

16

17

17

18

21

23

24

24

26

30

Output

4

Note

In the first sample, the optimal route is 0 → 10 (+1 gem) → 19 → 27 (+2 gems) → ...

In the second sample, the optimal route is 0 → 8 → 15 → 21 → 28 (+1 gem) → 36 (+1 gem) → 45 (+1 gem) → 55 (+1 gem) → 66 (+1 gem) → 78 (+1 gem) → ...

In the third sample, the optimal route is 0 → 7 → 13 → 18 (+1 gem) → 24 (+2 gems) → 30 (+1 gem) → ...

Codeforces (c) Copyright 2010-2021 Mike Mirzayanov

The only programming contests Web 2.0 platform

Server time: Apr/16/2021 17:20:11 (f2).

Desktop version, switch to mobile version.

Supported by

User lists

Name |
---|