//#include "/Users/priya/Desktop/competitiveProgrammingDocuments/VP/Header.h"
#include <bits/stdc++.h>
//freopen ("/Users/priya/Desktop/B-small-attempt1.in","r",stdin);
//freopen ("/Users/priya/Desktop/B-small-attempt1.out","w",stdout);
using namespace std;
#define ll long long int
#define ull unsigned long long
#define ul unsigned long
#define ios ios::sync_with_stdio(0);cin.tie(0);
#define eps 1e-4
#define PI acos(-1.0)
#define printarray(a,n)   for(ll i=1;i<=n;i++) cout<<ar[i]<<" ";
#define DBN1(a)           cerr<<#a<<"="<<(a)<<"\n"
#define DBN2(a,b)         cerr<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<"\n"
#define DBN3(a,b,c)       cerr<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<"\n"
#define DBN4(a,b,c,d)     cerr<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<"\n"
#define DBN5(a,b,c,d,e)   cerr<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<"\n"
#define DBN6(a,b,c,d,e,f) cerr<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<", "<<#f<<"="<<(f)<<"\n"
#define DA(a,n) cerr<<#a<<"=["; printarray(a,n); cerr<<"]\n"
//ll some_primes[10] = {100271, 500179, 1000003, 2000227, 5000321, 98765431}
//const int INF = 0x3ffffff;
const int N = 5000020;
const int mod = 1000000007;
//const int MAX = 100000128;
//const int MAX1 = 200;
//const int MAXN = 10000;
//const int maxN = 10000;
//const int C = 1000000000;
//const int MOD = 1000000009;
//const int SN = 1 << 18;
//88th fibonacci number is nearly 10^18
//pow(n,floor(log(x)/log(n)) -> smallest power of n than given number
/*
 WHERE WISHES ARE GRANTED
 When people bring you down,
 You shall rise,
 Never back down,
 Practice everyday,
 Till the last day....
*/
ll n;
ll ar[N];
int main(){
    cin >> n;
    for(ll i = 1; i <= n; i ++) cin >> ar[i];
    ll ans = 0;
    sort(ar + 1 , ar +n + 1);
    for(ll i = 1; i <= n; i ++){
        ll val = ar[i];
        ll temp = 0;
        for(ll j = i; j <= n; j ++) if(ar[j] - ar[i] <= 1) temp ++;
        ans = max(ans , temp);
    }
    cout << ans << endl;
    return 0;
}