#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector< vi > vvi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<pii> vii;
typedef vector< vii > vvii; 
typedef set<int> si;
typedef vector<si > vsi;
typedef set< pii> sii;
typedef unordered_map<int,int> umii;
typedef map<int,int> mii;
typedef priority_queue<int> pqi;
typedef priority_queue<pii> pqii;
#define mset(mas,val) memset(mas,val,sizeof(mas))
#define filln(x,val) fill_n(x.begin(),sz(x),val)
#define all(x) x.begin(),x.end()
#define fi first
#define se second
#define pres(a,x) x.find(a)!=x.end()
#define cpres(a,x) find(all(x),a)!=x.end()
#define pb push_back
#define mp make_pair
#define sz(x) x.size()
#define szfor(i,x) for(size_t i=0;i<sz(x);i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define fo(i,a,b) for(int i=a;i<b;i++)
#define fd(i,a,b) for(int i=a;i>b;i--) 
#define tr(it,x) for(auto it=x.begin();it!=x.end();it++)
#define rtr(it,x) for(auto it=x.rbegin();it!=x.rend();it++)
#define fast_io ios_base::sync_with_stdio(0);
#define accuracy  int precision = numeric_limits<double>::digits10;
ll MOD=1e9+7;
ll MAX=1e17;

int main(){
	fast_io;
	int n;cin>>n;
	int a[n];
	rep(i,n)cin>>a[i];
	int b[n],c[n],m;
	rep(i,n){
		b[i]=c[i]=0;
		int k=a[i];
		rep(j,n){
			if(a[j]==k){b[i]++;c[i]++;}
			if(a[j]==k+1)b[i]++;
			if(a[j]==k-1)c[i]++;
		}
		m=i ? max(m,max(b[i],c[i])) : max(b[i],c[i]);
	}
	cout<<m<<endl;
}