#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
  int n; cin >> n;
  vector<int> ar(n); for_each(ar.begin(), ar.end(), [](int& e){cin >> e;});
  sort(ar.begin(), ar.end());
  int answer = 0;
  vector<vector<int>> vanswer(n); auto vitr = vanswer.begin();
  vitr->push_back(ar[0]);
  ++answer;
  for(int i = 1; i < n; ++i)
  {
    if(!vitr->empty() && ar[i] - vitr->front() < 2)
    {
      //vitr->push_back(current);
      vitr->push_back(ar[i]);
      ++answer;
    }
    if(ar[i] - vitr->front() > 1)
    {
      ++vitr;
      vitr->push_back(ar[i]);
      answer = 1;
    }
  }
  
  answer = 0;
  for_each(vanswer.begin(), vanswer.end(), [&](auto& i){ if(i.size() > answer) answer = i.size();});
  cout << answer;
  return 0;
}