#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  vector<int> A(N);

  for (int &i : A) cin >> i;
  sort(A.begin(), A.end());

  for (int i = A.size() - 1; i >= 0; i--) {
    if (A.at(A.size() - 1) > A.at(i) + 1)
      A.pop_back();
  }

  cout << A.size() << endl;
}