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)

N = int(input())
A = list(map(int,input().split()))
ans = 0
l = []
A_sl = list(set(A))
if len(A_sl) == 1:
    print(len(A))
elif len(A_sl) == 2:
    if A_sl[1] - A_sl[0] <= 2:
        print(len(A))
    else:
        count_l = A.count(A_sl[1])
        count_s = A.count(A_sl[0])
        print(max(count_l,count_s)) 
else:
    for i in range(min(A),max(A) + 1):
        count_i = A.count(i)
        l.append(count_i)
    for i in range(2,max(A)-min(A)+1):
        if i == 2:
            ans = l[0] + l[1] + l[2]
            edge = l[0]
        elif l[i] > edge:
            ans = l[i-2] + l[i-1] + l[i]
            edge = l[i]
    print(ans)