#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;
    cin >> n;
    vector<int> a(n);
    for(int a_i = 0;a_i < n;a_i++)
    {
       cin >> a[a_i];
    }
   
     int i, j, min_idx;
 
    // One by one move boundary of unsorted subarray
    for (i=0; i < n-1; i++)
    {
        // Find the minimum element in unsorted array
        min_idx = i;
        for (j = i+1; j < n; j++)
          if (a[j] < a[min_idx])
            min_idx = j;
 
        // Swap the found minimum element with the first element
       int temp=a[min_idx];
        a[min_idx]=a[i];
        a[i]=temp;
    }
          int max=0;int max1;
    for(int i=0;i<n-1;i++)
        {max1=0;
        int j=i;
         int c=i;
       
         while((a[j]-a[c]==0)||(a[j]-a[c]==1)||(a[j]-a[c]==-1))
        {max1++;
         j++;
        }
       if(max1>max)
           max=max1;
        }
    
    cout<<max;
    
    return 0;
}