#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
#define pb push_back
#define mp make_pair
#define N 10005



int main()
{
//    freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
    ll n,arr[110];
    cin>>n;

    for(ll i=0;i<n;i++) cin>>arr[i];

    ll c1=0,c2=0,res=0;

    for(ll i=0;i<n;i++)
    {
        c1=0;c2=0;
        for(ll j=0;j<n;j++)
        {
            ll temp1=arr[i],temp2=arr[j];
            if(temp1==temp2||temp1==temp2-1) c1++;
            if(temp1==temp2||temp1==temp2+1) c2++;
        }
        res=max(res,max(c1,c2));
    }

    cout<<res<<endl;
    return 0;
}