#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 long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 998244353;
// constexpr int MOD = 1000000007;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int 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() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  constexpr int M = 2000;
  int n; cin >> n;
  vector<int> a(n); REP(i, n) cin >> a[i], --a[i];
  ll ans = 0;
  REP(i, n) {
    array<int, M> l{}, r{};
    FOR(j, i + 1, n) ++r[a[j]];
    int ways = 0;
    FOR(j, i + 1, n) {
      if (a[j] >= a[i] + 12) ways -= l[a[j] - 1];
      --r[a[j]];
      if (a[j] == a[i] + 10) ans += ways;
      if (a[j] >= a[i] + 11 && a[j] + 1 < M) ways += r[a[j] + 1];
      ++l[a[j]];
    }
  }
  cout << ans << '\n';
  return 0;
}