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

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

int main() {
  int N;
  cin >> N;

  vector<int> a(N);

  rep(i, N) cin >> a[i];

  sort(a.begin(), a.end());

  int ans = 1;

  rep(i, N-1) {
    if (a[i] + 1 >= a[i+1]) ans++;
  }

  cout << ans << endl;



}