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(){
    int n;
    int list[100000];
    scanf("%d", &n);
    int max = 0;
    for (int i = 0; i < n; ++i){
        scanf("%d", &list[i]);
        if (list[i] > max)
            max = list[i];
    }
    max += 2;
    int win = 0;
    for (int i = 0; i < max; ++i){
        int total = 0;
        for(int j = 0; j < n; ++j){
            if ((list[j]-1== i) || (list[j] == i) || (list[j]+1 == i))
                total += 1;
        }
        if (total > win)
            win = total;
    }
    printf("%d\n", win);

    return 0;
}