#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr ll LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n; cin >> n;
  vector<ll> a(n); REP(i, n) cin >> a[i];
  sort(ALL(a));
  vector<ll> mod2[2];
  REP(i, n) mod2[a[i] & 1].emplace_back(a[i]);
  ll ans = 0;
  for (int i = 0; i + 1 < n; ++i) {
    if (a[i + 1] == a[i] + 1) {
      int j = a[i + 1] & 1, idx = lower_bound(ALL(mod2[j]), a[i + 1]) - mod2[j].begin();
      int lb = idx, ub = mod2[j].size();
      while (ub - lb > 1) {
        int mid = (lb + ub) >> 1;
        (mod2[j][mid] == a[i + 1] + (mid - idx) * 2 ? lb : ub) = mid;
      }
      ans += lb - idx + 1;
    }
  }
  cout << ans + n << '\n';
  return 0;
}