#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
       int n,count=0,max=0;
         cin>>n;
          int a[n];
        for(int i=0;i<n;i++){
                cin>>a[i];
        }
   sort(a,a+n);
     int num=n;
           for(int i=0;i<num;i++){
                              count=1;
                              for(int j=i+1;j<num;j++){
                                      if(abs(a[j]-a[i])<=1){
                                             count++;
                                      }
                              }
               if(count>max){
                     max=count;
               }
                    }
           
              
           
    cout<<max<<"\n";
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}