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 cc : array [-1..100001] of longint ;
    max,n,a,b,c,d,e,f,g : longint ;
begin
 readln(n);
 for a:=1 to n do
  begin
   read(g);
   cc[g-1]:=cc[g-1]+1;
   cc[g]:=cc[g]+1;
   cc[g+1]:=cc[g+1]+1;
  end;
 for a:=-1 to 100001 do
  if cc[a]>max then
   max:=cc[a];
 writeln(max); 
end.