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 Python (3.4.3) (judge verdict: Wrong Answer)

def main():
    t = input()
    if t == "1":
        print(input())
        exit(0)
    li = [int(v) for v in input().split(' ')]
    s_li = sorted(li)
    count = 0
    for v in s_li:
        t_c = 0
        for vv in s_li:
            if v == vv or v - 1 == vv or v + 1 == vv:
                t_c += 1
        if t_c > count:
            count = t_c

    print(count)



if __name__ == '__main__':
    main()