#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) {a = max(a, b);}
template<class T> void chmin(T& a, const T& b) {a = min(a, b);}
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

struct S {
    ll m1, m2, M;
};

S op(S x, S y) {
    ll M = max(x.M, y.M);
    ll m1, m2;
    if (x.m2 <= y.m1) {
        m1 = x.m1, m2 = x.m2;
    } else if (y.m2 <= x.m1) {
        m1 = y.m1, m2 = y.m2;
    } else {
        m1 = x.m1, m2 = y.m1;
        if (m1 > m2) swap(m1, m2);
    }
    return {m1, m2, M};
}

constexpr ll INF = 1002003004005006007;
S e() {
    return {INF, INF, -INF};
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    VI a(n);
    vector<S> init_vec(n);
    rep(i, n) {
        cin >> a[i];
        init_vec[i] = {a[i], INF, a[i]};
    }
    segtree<S, op, e> seg(init_vec);
    ll ans = 0;
    rep(i, n) {
        auto g = [&](S x) {
            return x.M <= x.m1 + x.m2;
        };
        int r = seg.max_right(i, g);
        ans += max(0, r - i - 1);
    }
    cout << ans << endl;
}