#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,res=1,current_res=1,pivot=0;
    cin >> n;
    vector<int> a(n);
    for(int a_i = 0;a_i < n;a_i++){
       cin >> a[a_i];
    }
    sort(a.begin(),a.end());
    for(int i = 1; i < n;i++){
      if(abs(a[i] - a[pivot]) <= 1){
        current_res++;
      }else{
        res = max(res, current_res);
        pivot = i;
        current_res = 1;
      }
    }
    res = max(res, current_res);
    printf("%d",res);
    return 0;
}