#include<bits/stdc++.h>

using namespace std;
int arr [ 200 ];
int main()
{

int n ;
scanf("%d",&n);
int cnt = 0 , mx = 0 ;
for ( int i = 1 ; i <= n ; i ++ )cin >> arr [ i ];
sort(arr+1,arr+n+1);
for ( int i = 1; i <= n ; i ++ ){
        cnt = 1 ;int mn = arr[ i ] ;
    for ( int j = 1  ; j <= n ; j ++ ){
        if ( i == j )continue ;
        if ( abs ( arr [ i ] - arr [ j ] ) <= 1 ){
                if ( mn > arr[ j ]){
                    mn = arr [ j ];
                }
                if ( abs ( mn - arr [ j ]) <= 1 )
            cnt ++ ;
        }

            }mx = max(mx , cnt );
}
cout << mx << endl;


return 0;
}