#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 */  
    long long int n;
    cin>>n;
    long long int ar[n+1];
    for(long long int i=0;i<n;i++)
        cin>>ar[i];
    long long int cc=0;
    for(long long int i=0;i<n-1;i++)
    {
        long long int c=0;
        for(long long int j=0;j<n;j++)
        {
            if(ar[i]-ar[j]<=1 && ar[i]-ar[j]>=0)
            {
                c++;
            }
        }
        cc=max(c,cc);
    }
    cout<<cc<<endl;
    return 0;
}