#include <bits/stdc++.h>
#define ll  long long
#define f first
#define s second  
#define pii pair< ll,ll > 
#define pb push_back
#define sc(x) scanf("%d",&x)
#define lw lower_bound
#define llmax 1e9
#define mod 1000000007
#define block 350
#define MAX 100010
using namespace std;
priority_queue <pii,vector<pii> > q1 ;
map <ll,ll> mii ;
map <ll,ll> ::iterator iit ;
map <string ,ll> msi ;
map <string ,ll> ::iterator sit ;
map <char ,ll > mci ;
map <char ,ll > ::iterator cit ;
vector <ll > v ;
vector <ll > ::iterator vit ;
map <pii,bool > mp ;
int a[110];
int main  () {
    ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    int n;cin >>n ;
    for (int i=0;i<n;i++) cin >>a[i] ;
    sort (a,a+n) ;
    int p1=0,p2=0,ans=0 ;
    while (p1<n&&p2<n) {
        while (p2<n&&a[p2]-a[p1]<=1)p2++ ;
        if (p2==n) {
            ans=max(ans,p2-p1) ;
            break ;
        }
        else {
            ans=max(ans,p2-p1) ;
            while (a[p2]!=a[p1]) p1++ ;
        }
    }
    cout <<ans<<"\n" ;
}