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: Accepted)

function Main(input) {
    input = input.split("\n")
    const n = parseInt(input[0])
    var A = input[1].split(" ")
    
    var tmp = {}
    for (var i=0;i<100000;i++){
        tmp[i]=0
    }

    for (var i=0;i<n;i++){
        var a = parseInt(A[i])
        tmp[a-1]++
        tmp[a]++
        tmp[a+1]++
    }

    var ans = 0
    for (var i=0;i<100000;i++){
        ans = Math.max(ans,tmp[i])
    }
    
    console.log(ans)

}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));