#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 beg = 0;
    int end = 0;
    int max_beg = 0;
    int max_end = 0;
    int val = 0;
    beg = 0;
    val = a[0];
    for(int a_i = 1;a_i < n;a_i++){
        if (a[a_i] != val) {
            if (a[a_i] > val + 1 ) {
                end = a_i - 1;
                val = a[a_i];
                if (end - beg > max_end - max_beg) {
                    max_end = end;
                    max_beg = beg;
                }
                beg = a_i;
            }
        }
    }
    end = n - 1;
    if (end - beg > max_end - max_beg) {
        max_end = end;
        max_beg = beg;
    }
    cout << (max_end - max_beg + 1) << endl;
    return 0;
}