#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 maxLen = 0;
    sort (a.begin(), a.begin()+n);
    for(int i = 0; i < n; i++){
        //vector<int>tempList;
        int len = 0;
        for(int j = i; j < n; j++){
            if(abs(a[j] - a[i]) <= 1){
                //tempList.push_back()
                len += 1;
            }
        }
        maxLen = max(maxLen, len);
    }
    
    cout << maxLen << endl;
    
    return 0;
}