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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <iostream>
#include <queue>
using namespace std;
int ret=0,cn=0;
priority_queue<int> pq;
int func (int arr[],int n,int i,int add)
{
        cn=0;
        if (i>=0) {
        if (i>=n) return ret;
        else {
        arr[i]+=add;
        for (int j=0;j<n ;j++)
          if (arr[i]==arr[j])
              cn+=1;
         ret = max(ret,cn);
        }
        //if (cn >ret )return cn;

//       for (int j=0;j<n;j++)
//        cout <<arr[j]<<" ";
//        cout <<endl;
//       cout <<cn<<endl;
        }
        int ret1=func(arr,n,i+1,1);
        int ret2=func(arr,n,i+1,0);
        int ret3=func(arr,n,i+1,-1);
        ret=max(max(ret1,ret2),ret3);

}
int main()
{
  int n;
  cin>>n;
  int arr[n];
  for (int i=0;i<n;i++)
    cin>>arr[i];
   //cout << func(arr,n,-1,1);
   cout <<max(func(arr,n,0,0),max (func(arr,n,0,1),func(arr,n,0,-1)))<<endl;

    return 0;
}