#include <bits/stdc++.h>
using namespace std;

#define REP(i, a, b) for (int i = a; i <= b; i++)
#define FOR(i, n) for (int i = 0; i < n; i++)
#define foreach(it, ar) for ( typeof(ar.begin()) it = ar.begin(); it != ar.end(); it++ )
#define fill(ar, val) memset(ar, val, sizeof(ar))
#define PI 3.1415926535897932385
#define uint64 unsigned long long
#define Int long long
#define int64 long long
#define all(ar) ar.begin(), ar.end()
#define pb push_back
#define ff first
#define ss second
#define bit(n) (1<<(n))
#define Last(i) ( (i) & (-i) )
#define sq(x) ((x) * (x))
#define INF INT_MAX
#define mp make_pair


int main ( )
 {
    int n ;
    cin >>  n ;
    vector<int>a( n )  ;
    FOR( i, n ) cin >>  a[i]  ;
    int cnt = 0 ;

     for( int i = 0 ; i <  n ; i ++ )
       {
          int num =  a[i] ;
          int ma =   1   ;
          int ma1 = 1  ;

          for( int j = 0 ; j < n ; j ++ )
            {
               if(  i!= j &&  ( a[i] - a[j]  == 1 || a[i] - a[j] == 0 ) )  ma ++ ;

            }

            for( int j = 0 ; j < n ; j ++ )
            {
               if(  i!= j &&   ( a[i] - a[j]  == -1 || a[i] - a[j] == 0 ) ) ma1 ++ ;

            }

           cnt = max( cnt , max( ma , ma1 ) )  ;



       }

       cout<<cnt<<endl;




 }