#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.begin() + n);
 
    int MAX = 0;
    for(int i = 0; i < n - 1; i++) {
       int foundMaxIndex = 0;
       for(int j = i + 1; j < n; j++) {
           if (a[j] - a[i] <= 1) {
               foundMaxIndex = j;
               MAX = max(MAX, foundMaxIndex - i + 1);
               //cout << "max " << MAX << endl;
           }
       }
        
    }
    
    cout << MAX << endl;
    return 0;
}