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

// Segment Tree
template<class Monoid> struct SegTree {
    using Func = function<Monoid(Monoid, Monoid)>;

    // core member
    int SIZE;
    Func F;
    Monoid IDENTITY;
    
    // data
    int offset;
    vector<Monoid> dat;

    // constructor
    SegTree() {}
    SegTree(int n, const Func &f, const Monoid &identity)
    : SIZE(n), F(f), IDENTITY(identity) {
        offset = 1;
        while (offset < n) offset *= 2;
        dat.assign(offset * 2, IDENTITY);
    }
    void init(int n, const Func &f, const Monoid &identity) {
        SIZE = n;
        F = f;
        IDENTITY = identity;
        offset = 1;
        while (offset < n) offset *= 2;
        dat.assign(offset * 2, IDENTITY);
    }
    int size() const { return SIZE; }
    
    // set, a is 0-indexed //
    // build(): O(N)
    void set(int a, const Monoid &v) { dat[a + offset] = v; }
    void build() {
        for (int k = offset - 1; k > 0; --k)
            dat[k] = F(dat[k*2], dat[k*2+1]);
    }
    void build(const vector<Monoid> &vec) {
        for (int a = 0; a < vec.size() && a + offset < dat.size(); ++a)
            set(a, vec[a]);
        build();
    }
    
    // update a, a is 0-indexed, O(log N)
    void update(int a, const Monoid &v) {
        int k = a + offset;
        dat[k] = v;
        while (k >>= 1) dat[k] = F(dat[k*2], dat[k*2+1]);
    }
    
    // get [a, b), a and b are 0-indexed, O(log N)
    Monoid get(int a, int b) {
        Monoid vleft = IDENTITY, vright = IDENTITY;
        for (int left = a + offset, right = b + offset; left < right;
        left >>= 1, right >>= 1) {
            if (left & 1) vleft = F(vleft, dat[left++]);
            if (right & 1) vright = F(dat[--right], vright);
        }
        return F(vleft, vright);
    }
    Monoid get_all() { return dat[1]; }
    Monoid operator [] (int a) const { return dat[a + offset]; }
    
    // get max r that f(get(l, r)) = True (0-indexed), O(log N)
    // f(IDENTITY) need to be True
    int max_right(const function<bool(Monoid)> f, int l = 0) {
        if (l == SIZE) return SIZE;
        l += offset;
        Monoid sum = IDENTITY;
        do {
            while (l % 2 == 0) l >>= 1;
            if (!f(F(sum, dat[l]))) {
                while (l < offset) {
                    l = l * 2;
                    if (f(F(sum, dat[l]))) {
                        sum = F(sum, dat[l]);
                        ++l;
                    }
                }
                return l - offset;
            }
            sum = F(sum, dat[l]);
            ++l;
        } while ((l & -l) != l);  // stop if l = 2^e
        return SIZE;
    }

    // get min l that f(get(l, r)) = True (0-indexed), O(log N)
    // f(IDENTITY) need to be True
    int min_left(const function<bool(Monoid)> f, int r = -1) {
        if (r == 0) return 0;
        if (r == -1) r = SIZE;
        r += offset;
        Monoid sum = IDENTITY;
        do {
            --r;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!f(F(dat[r], sum))) {
                while (r < offset) {
                    r = r * 2 + 1;
                    if (f(F(dat[r], sum))) {
                        sum = F(dat[r], sum);
                        --r;
                    }
                }
                return r + 1 - offset;
            }
            sum = F(dat[r], sum);
        } while ((r & -r) != r);
        return 0;
    }
    
    // debug
    friend ostream& operator << (ostream &s, const SegTree &seg) {
        for (int i = 0; i < seg.size(); ++i) {
            s << seg[i];
            if (i != seg.size()-1) s << " ";
        }
        return s;
    }
};

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;
        // SegTree<ll> seg(n,[](ll a, ll b){return a+b;},0ll);
        for (int j = i+1; j < n; j++) {
            if(ms.find(j)!=ms.end())ms.erase(j);
            if(a[i]+10==a[j]){
                ans += ms.size();
            }
            for (auto e : p[j]) {
                if(a[j]>=a[i]+11){
                    ms.insert(e);
                }
            }
        }
    }
    std::cout << ans << std::endl;
}