#include <cstdio>
#include<bits/stdc++.h>
using namespace std;
#define up(a) a.begin(),a.end()
#define max_arr(a) *max_element(up(a))
#define min_arr(a) *min_element(up(a))
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define vi vector<int>
#define vp vector<pair<int,int> >
#define pi pair<int,int>
#define pr printf
#define sc(a) scanf("%d",&a);
#define endl "\n"
#define ll long long int
#define fore(i, l, r) for(int i = (l); i < (r); ++i)
#define forn(i, n) fore(i, 0, n)
#define fori(i, l, r) fore(i, l, (r) + 1)
#define cerr(x) cout<<x<<endl;
#define boost ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
const int inf = 2e9;
/*
forn(i,n)
  forn(j,n)d[i][j]=(i!=j)?inf:0;
*/

int main(){
  boost;
  int n;cin>>n;
  int a[n];
  forn(i,n)cin>>a[i];
  sort(a,a+n);
  int min=*min_element(a,a+n);
  int max=*max_element(a,a+n);
  int sum[max-min+1]; 
  for(int i=min;i<=max;i++){
      sum[i-min]=0;
      forn(j,n){
         if(a[j]-i==0||a[j]-i==1)sum[i-min]++;
      }
    // cout<<sum[i-min]<<endl; 
  } 
  cout<<*max_element(sum,sum+(max-min+1));
 
  return 0;
}