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 (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <stdio.h>

int main()
{
    long long int n, i, j, max = - 1;
    scanf("%lld", &n);
    long long int arr[n];

    for(i=0; i<n; i++)
        scanf("%lld", &arr[i]);

    for(i=0; i<n; i++){
        int count = 1;
        for(j=0; j<n; j++){
            if(i != j){
                if(arr[j] == arr[i] || arr[j] + 1 == arr[i] || arr[j] - 1 == arr[i]){
                    count++;
                    if(count > max)
                        max = count;
                }
            }
        }
    }
    if(max == -1)
        printf("1");
    else
        printf("%lld", max);

    return 0;
}