#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 n;
vector<int> v;

int main(){
    cin >> n;
    v.resize(n);
    for(int i = 0; i < n; ++i)
        cin >> v[i];
    sort(v.begin(), v.end());
    
    vector<int>::iterator s = v.begin();
    vector<int>::iterator f = s;
    int maxcount = 1;
    while(s != v.end()) {
        s = upper_bound(f, v.end(), (*f + 1));
        maxcount = max(maxcount, (int)(s-f));
        f = upper_bound(f, v.end(), *f);
    }
    cout << maxcount << endl;

    return 0;
}