#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n;
    cin >> n;
    vector<int> a(n);
    for(int a_i = 0;a_i < n;a_i++){
       cin >> a[a_i];
    }
    int count=0,c1=0,c2=0;
    for(int i = 0;i < n;i++){
       for(int j=0;j<n;j++){
           if(a[j]==a[i] || a[j]==a[i]+1){
               c1++;
           }
           if(a[j]==a[i] || a[j]==a[i]+1){
               c2++;
           }           
       }
        if(count < c1){
            count=c1;
        }
        if(count < c1){
            count=c1;
        }
        c1=0;
        c2=0;
    }    
    cout<<count;
    return 0;
}