#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];
    }
    
    sort( a.begin(), a.end() );
    
    long maxCnt = -1;
    long currCnt = 1;
    long idx = 0;
    
    for (int i=1; i<n; i++)
    {
        if (a[i]-a[idx] > 1)
        {
            maxCnt = max(currCnt, maxCnt);
            currCnt = 1;
            idx = i;
        } 
        else
        {
            currCnt++;    
        }
    }
    
    maxCnt = max(currCnt, maxCnt);
    
    cout << maxCnt << endl;
    
    return 0;
}