#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

#include <atcoder/fenwicktree>


// a
// a + k + 10
// a + 10
// a + k + 11

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    int N;
    cin >> N;
    vector<int> A(N);
    for (auto &x : A) cin >> x;

    vector<int> idx(N);
    for (int i = 0; i < N; ++i) idx.at(i) = i;
    stable_sort(idx.begin(), idx.end(), [&](int i, int j) { return A.at(i) < A.at(j); });

    atcoder::fenwick_tree<int> fw(N);

    long long ret = 0;
    for (const int i : idx) {
        const int sum = fw.sum(0, i + 1);
        for (int j = i + 1; j < N; ++j) {
            if (A.at(j) == A.at(i) + 1) ret += sum;
        }
        vector<int> cntr(2001);
        int nbad = 0;
        for (int i1 = i - 1; i1 >= 0; --i1) {
            if (A.at(i1) + 10 == A.at(i)) {
                fw.add(i1, 1);
                fw.add(i, -1);
                ret -= nbad;
            }
            if (A.at(i1) > A.at(i)) nbad += cntr.at(A.at(i1) + 1);
            cntr.at(A.at(i1))++;
        }
    }
    cout << ret << '\n';
}