#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 curInterval = 0;
    int maxInterval = 1;
    vector<int>::iterator it1, it2;
    it1 = it2 = a.begin();
    
    while(it2 != a.end()) {
        ++it2;
        ++curInterval;
        if (it2 != a.end() && *it2 - *it1 <= 1) {
            continue;
        }
        
        maxInterval = max(curInterval, maxInterval);
        if (it2 == a.end())
            break;
        
        do {
            ++it1;
            --curInterval;
        } while(*it1 - *(it1 - 1) == 0);
    }
    
    cout << maxInterval;
    
    return 0;
}