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: Runtime Error)

#include <iostream>
#include <string>
#include <algorithm>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <numeric>

using namespace std;
int a[10010];
int ans[10010];

int main(){
   int n;
   cin>>n;
   for(int i=0;i<n;i++)cin>>a[i];
   sort(a,a+n);
   int a_max=a[n-1];
   int a_min=a[0];
   for(int i=0;i<n;i++){
      if(a[i]==a_min){
         ans[i]=upper_bound(a,a+n,a[i]+1)-lower_bound(a,a+n,a[i]);
      }
      else if(a[i]==a_min){
         ans[i]=upper_bound(a,a+n,a[i])-lower_bound(a,a+n,a[i]-1);
      }
      else ans[i]=upper_bound(a,a+n,a[i]+1)-lower_bound(a,a+n,a[i]-1);
   }
   int ans_max=0;
   for(int i=0;i<n;i++){
      ans_max=max(ans_max,ans[i]);
   }
   cout<<ans_max<<endl;
   
   
}