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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int n;
    cin>>n;
    vector<int>a(n);
    vector<int>b(100,0);
    int i,j,k,l=0;
    for(i=0;i<n;i++)
        {cin>>a[i];
        b[a[i]]++;}
     for(i=0;i<99;i++)
         {if((b[i]+b[i+1])>l)
         {l=b[i]+b[i+1];k=i;}
          
         }
    cout<<b[k]+b[k+1]<<endl;
    
    return 0;
}