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.h>
using namespace std;
int main()
{
	int n;
	cin >> n;
	int a[n],s[n],maxi=-1;
	memset(s,0,sizeof(s));
	for (int i=0;i<n;i++)
	{
		scanf("%d",&a[i]);
		if (a[i]==0)
		{
			s[a[i]]++;
			s[a[i]+1]++;
		}
		else if (a[i]==n-1)
		{
			s[a[i]]++;
			s[a[i]-1]++;
		}
		else
		{
			s[a[i]+1]++;
			s[a[i]]++;
			s[a[i]-1]++;
		}
	}
	for (int i=0;i<n;i++)
	{
		if (s[i]>maxi) maxi=s[i];
	}
	cout << maxi;
	return 0;
}