#include <iostream>

using namespace std;


int main(){
    int n,m,i,maxi,maxi1;
    cin >> n;
    int a[n],sum[n],sum1[n];
    m=0;
    for(i=0;i<n;i++)
    {cin>>a[i];    
     sum[i]=0;
     sum1[i]=0;}
     
    while(m<n)
    { 
        
        
         
          for(i=0;i<n;i++)
        { 
            if((a[m]-a[i])==1 || a[m]==a[i] )
            {sum[i]=sum[i]+1;}
           else
           {
               if((a[m]-a[i])==-1  || a[m]==a[i])
               {
                sum1[i]=sum1[i]+1;   
               }
               
           }    
        }    
        
        
        m++;
    }
    maxi=0;
    maxi1=0;
    
   for(i=0;i<n;i++)
   { if(sum[i]>maxi)
       {maxi=sum[i];}
    if(sum1[i]>maxi1)
        {maxi1=sum1[i];}
       
   }
    
 if(maxi1>maxi)
 cout<<maxi1;
 else
 cout<<maxi;    
    
    
    return 0;
}