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

using ll = long long;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  int n;
  cin >> n;
  assert(1 <= n && n <= 2e5);
  
  vector<ll> odd, even;
  set<int> odd_set, even_set;
  for (int i = 0; i < n; i++) {
    ll a;
    cin >> a;
    assert(1 <= a && a <= 1e18);
    if (a % 2 == 1) {
      odd.emplace_back(a);
      odd_set.insert(a);
    }
    else {
      even.emplace_back(a);
      even_set.insert(a);
    }
  }
  
  assert(odd_set.size() + even_set.size() == n);
  
  sort(odd.begin(), odd.end());
  sort(even.begin(), even.end());
  
  // sentinel
  odd.emplace_back(2e18 - 1);
  even.emplace_back(2e18);
  
  vector<ll> odd_acc(odd.size(), 1), even_acc(even.size(), 1);
  for (int i = odd_acc.size() - 2; i >= 0; i--) {
    if (odd.at(i) == odd.at(i + 1) - 2) odd_acc.at(i) += odd_acc.at(i + 1);
  }
  for (int i = even_acc.size() - 2; i >= 0; i--) {
    if (even.at(i) == even.at(i + 1) - 2) even_acc.at(i) += even_acc.at(i + 1);
  }
  
  ll ans = n;
  int even_it = 0;
  for (int i = 0; i < odd.size() - 1; i++) {
    while (even.at(even_it) <= odd.at(i)) even_it++;
    if (even.at(even_it) == odd.at(i) + 1) ans += even_acc.at(even_it);
  }
  int odd_it = 0;
  for (int i = 0; i < even.size() - 1; i++) {
    while (odd.at(odd_it) <= even.at(i)) odd_it++;
    if (odd.at(odd_it) == even.at(i) + 1) ans += odd_acc.at(odd_it);
  }
  
  cout << ans << '\n';
}