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

int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (auto& a_ : a) {
    cin >> a_;
  }
  sort(a.begin(), a.end());
  int ans = 1;
  for (int i = 1; i < n; i++) {
    if (a[i - 1] + 1 >= a[i])
      ans++;
  }
  cout << ans << '\n';
  return 0;
}