#include <bits/extc++.h>

int main() {
    using namespace std;
    unsigned N;
    cin >> N;
    vector<unsigned> A(N);
    for (auto &&a : A)
        cin >> a;

    unsigned long ans{};
    unordered_map<unsigned, unsigned> counter;
    for (unsigned i{}; i < N; ++i) {
        ++counter[A[i]];
        unordered_map<unsigned, unsigned> counter_sub;
        for (unsigned j{N}; j-- > i;) {
            ++counter_sub[A[j]];
            if (A[i] > A[j])
                ans += counter[A[j] - 10] * counter_sub[A[i] + 1];
        }
    }

    cout << ans << endl;
    return 0;
}