#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,x;
    int q,w,e;
    int b[100];
    for (int i=0;i<100;i++)
        b[i]=0;
    cin >>n;
    int a [100];
    for(int i=0;i <n;i++)
    {  cin>>a[i];
    b[a[i]]++;
    }q=0;w=0;
    for(int i=1;i <100;i++)
     if (w <b [i]+b [i-1])
    { q=a[i];w=b [i]+b [i-1];}
    cout<<w;
    return 0;
}