#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());
    
    int l = 0;
    int h = 0;
    int dif = 0;
    
    while(l < n && h < n) {
        int d = a[h] - a[l];
        
        if (d <= 1) {
            dif = max(dif, h - l + 1);
            h++;
        } else {
            l++;
        }
    }
    
    cout << dif << endl;
    
    return 0;
}