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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

var fs = require("fs");
Main(fs.readFileSync("/dev/stdin","utf-8"));

function Main(input){
  input = input.split("\n");
  N = parseInt(input[0],10);
  input=input[1].split(" ");
  input=input.map(function(value){
    return parseInt(value,10);
  });
  var input_count=new Array(100001).fill(0);
  for(var i in input){
    input_count[input[i]]+=1;
  }
  var ans=0;
  for(var i in input){

    var tmp =input_count[input[i]-1]+input_count[input[i]]+input_count[input[i]+1];
    if(ans<tmp) ans=tmp;
  }
  console.log(ans);
}