#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;

int N, A[101010], cnt = 1;

int main() {
  cin >> N;
  for (int i = 0; i < N; i++) cin >> A[i];
  sort(A, A + N);
  for (int i = 0; i < N - 1; i++) {
    if (A[i] + 1 >= A[i + 1]) cnt++;
  }
  cout << cnt << endl;
  return 0;
}