Problem:
Score : 300 points

Problem Statement

You are given an integer sequence of length N, a_1,a_2,...,a_N.

For each 1≤i≤N, you have three choices: add 1 to a_i, subtract 1 from a_i or do nothing.

After these operations, you select an integer X and count the number of i such that a_i=X.

Maximize this count by making optimal choices.

Constraints

1≤N≤10^5

0≤a_i<10^5 (1≤i≤N)

a_i is an integer.

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 .. a_N

Output

Print the maximum possible number of i such that a_i=X.

Sample Input 1

7
3 1 4 1 5 9 2

Sample Output 1

4

For example, turn the sequence into 2,2,3,2,6,9,2 and select X=2 to obtain 4, the maximum possible count.

Sample Input 2

10
0 1 2 3 4 5 6 7 8 9

Sample Output 2

3

Sample Input 3

1
99999

Sample Output 3

1

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main(void){
  int n; //要素数
  int check;

  scanf("%d", &n);
  int b[n];//整数列

  int i , ii;//ループ用

  for(i = 0; i < n; i++){
    scanf("%d", &b[i]);
  }//整数列の値を取得


  int countmax = 0, count = 0;

  for(i = 0; i < n; i++){
    for(ii = i; ii < n; ii++){
      if((b[ii] == b[i]) || (b[ii] == b[i] + 1) || (b[ii] == b[i] - 1)){
        count++;
      }
    }

    if(count > countmax){
      countmax = count;
    }

    count = 0;
  }//ここではXを0から1ずつ増やして調べる

  printf("%d", countmax);
}