typedef long long ll;
typedef long double ld;
#include <bits/stdc++.h>
using namespace std;
#define int long long

signed main(){
    ll n;
    std::cin >> n;
    vector<ll> a(n);
    vector<vector<ll>> p(n);//,p10(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    for (int i = 0; i < n; i++) {
        for (int j = i+1; j < n; j++) {
            if(a[i]+1==a[j]){
                p[i].push_back(j);
            }
        }
    }
    
    ll ans = 0;
    for (int i = 0; i < n; i++) {
        multiset<ll> ms;
        for (int j = i+1; j < n; j++) {
            if(j>i+1){
                for (auto e : p[j-1]) {
                    ms.insert(e);
                }
            }
            ms.erase(j);
            if(a[i]+10==a[j]){
                ans += ms.size();
            }
        }
    }
    std::cout << ans << std::endl;
}