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 Pascal (FPC 2.6.2) (judge verdict: Accepted)

var a:array[-1..100005]of longint;
    n,i,max,min,l:longint;
begin
    readln(n);min:=-1;max:=maxlongint;
    for i:=1 to n do begin
        read(l);
        inc(a[l]);inc(a[l-1]);inc(a[l+1]);
        if (l+1)>max then max:=l+1;
        if (l-1)<min then min:=l-1;
        if min<0 then min:=0;
        if max>100000then max:=100000;
    end;l:=0;
    for i:=min to max do
    if a[i]>l then l:=a[i];
    writeln(l);
end.