#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 123, inf = 1e9 + 123, mod = 1e9 + 7;
const long long INF = 1e18;
int n, a[N];
int main() {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(0);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  reverse(a + 1, a + n + 1);
  int mn = inf;
  for (int i = 1; i <= n; i++) {
    if (a[i] + 1 < mn) {
      a[i]++;
      mn = a[i];
    } else {
      if (a[i] < mn) {
        mn = a[i];
      } else if (a[i] - 1 < mn && a[i] > 1) {
        mn = a[i] - 1;
        a[i]--;
      }
    }
  }
  set<int> st;
  for (int i = 1; i <= n; i++) {
    st.insert(a[i]);
  }
  cout << st.size();
  return 0;
}
