#include <bits/stdc++.h>

#define pb push_back
#define mp make_pair
#define mt make_tuple
#define ll long long unsigned
#define pii pair<int,int>
#define tii tuple <int,int,int>
#define N 1000005
#define mod 2000003
#define X first
#define Y second
#define eps 0.0000000001
#define all(x) x.begin(),x.end()
#define tot(x) x+1,x+n+1
using namespace std;
int sol,sc,i,n,a[110],x;
int main()
{
    cin.sync_with_stdio(0);
    cout.sync_with_stdio(0);
    cin>>n;
    for(i=1; i<=n; i++)
    {
        cin>>x;
        a[x]++;
    }
    for(i=0; i<=101; i++)
    {

        if(sc<a[i]+a[i+1])
        {
            sc=a[i]+a[i+1];
            sol=i+1;
        }
    }
    cout<<sc;
    return 0;
}