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


int main() {
    int n;
    cin>>n;
    int a[n],k,ans=0;
    for(int i=0;i<n;i++)
        cin>>a[i];
    for(int i=0;i<100;i++)
    {
        k=0;
        for(int j=0;j<n;j++)
        {
            //cout<<a[j]<<": "<<k<<", ";
            if(a[j]==i||a[j]==i+1)
                k++;
        }
        //cout<<endl;
        //cout<<"k: "<<k<<",ans:"<<ans<<endl;
        if(k>ans)
            ans=k;
    }
    cout<<ans;
    return 0;
    
}