#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int n,max=0;
    cin >> n;
    vector<int> a(n);
    vector <int> cp(n,0),cm(n,0),b(n,0);
    for(int i = 0;i < n;i++){
       cin >> a[i];
    }
    for(int i=0;i<n;i++)
        {
        for(int j=0;j<n;j++)
            {
            if((a[j]==a[i]+1)||(a[j]==a[i])){cp[i]++;}
            if((a[j]==a[i]-1)||(a[j]==a[i])){cm[i]++;}
        }
        if(cp[i]>cm[i]){b[i]=cp[i];}
        else{b[i]=cm[i];}
        if(max<b[i]){max=b[i];}
    }
    cout<<max;
    return 0;
}