#include <bits/stdc++.h>

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,b,n) for(ll a = b;a < n;a++)

#include <bits/stdc++.h>
using namespace std;

template<typename T>
void chmax(T& reference, T value) {
	reference = max(reference, value);
}

template<typename T>
void chmaxmap(map<T, T>& m, T key, T value) {
	if (m.count(key)) {
		chmax(m[key], value);
	}
	else {
		m[key] = value;
	}
}

template<typename T>
void chmin(T& reference, T value) {
	reference = min(reference, value);
}

int ceil_pow2(int n) {
    int x = 0;
    while ((1U << x) < (unsigned int)(n)) x++;
    return x;
}

template <class S, S(*op)(S, S), S(*e)()> struct segtree {
public:
    segtree() : segtree(0) {}
    segtree(int n) : segtree(std::vector<S>(n, e())) {}
    segtree(const std::vector<S>& v) : _n(int(v.size())) {
        log = ceil_pow2(_n);
        size = 1 << log;
        d = std::vector<S>(2 * size, e());
        for (int i = 0; i < _n; i++) d[size + i] = v[i];
        for (int i = size - 1; i >= 1; i--) {
            update(i);
        }
    }

    void set(int p, S x) {
        assert(0 <= p && p < _n);
        p += size;
        d[p] = x;
        for (int i = 1; i <= log; i++) update(p >> i);
    }

    S get(int p) {
        assert(0 <= p && p < _n);
        return d[p + size];
    }

    S prod(int l, int r) {
        assert(0 <= l && l <= r && r <= _n);
        S sml = e(), smr = e();
        l += size;
        r += size;

        while (l < r) {
            if (l & 1) sml = op(sml, d[l++]);
            if (r & 1) smr = op(d[--r], smr);
            l >>= 1;
            r >>= 1;
        }
        return op(sml, smr);
    }

    S all_prod() { return d[1]; }

    template <bool (*f)(S)> int max_right(int l) {
        return max_right(l, [](S x) { return f(x); });
    }
    template <class F> int max_right(int l, F f) {
        assert(0 <= l && l <= _n);
        assert(f(e()));
        if (l == _n) return _n;
        l += size;
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!f(op(sm, d[l]))) {
                while (l < size) {
                    l = (2 * l);
                    if (f(op(sm, d[l]))) {
                        sm = op(sm, d[l]);
                        l++;
                    }
                }
                return l - size;
            }
            sm = op(sm, d[l]);
            l++;
        } while ((l & -l) != l);
        return _n;
    }

    template <bool (*f)(S)> int min_left(int r) {
        return min_left(r, [](S x) { return f(x); });
    }
    template <class F> int min_left(int r, F f) {
        assert(0 <= r && r <= _n);
        assert(f(e()));
        if (r == 0) return 0;
        r += size;
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!f(op(d[r], sm))) {
                while (r < size) {
                    r = (2 * r + 1);
                    if (f(op(d[r], sm))) {
                        sm = op(d[r], sm);
                        r--;
                    }
                }
                return r + 1 - size;
            }
            sm = op(d[r], sm);
        } while ((r & -r) != r);
        return 0;
    }

private:
    int _n, size, log;
    std::vector<S> d;

    void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};

struct S {
    ll v1;
    ll v2;
    ll m;

    bool ok() const {
        return m <= v1 + v2;
    }
};

S op(S left, S right) {
    ll v1, v2;
    if (left.v1 < right.v1) {
        v1 = left.v1;
        v2 = min(left.v2, right.v1);
    }
    else {
        v1 = right.v1;
        v2 = min(left.v1, right.v2);
    }
    return { v1, v2, max(left.m, right.m) };
}
constexpr ll INF = 1e15;
S e() {
    return S{INF,INF,-INF};
}


int main() {
    ll n;
    cin >> n;
    vector<ll> as(n);
    rep(i, n) cin >> as[i];
    segtree<S, op, e> tree(n+1);
    rep(i, n) tree.set(i, { as[i], INF, as[i] });
    tree.set(n, { -INF, -INF, INF });
    ll sum = 0;
    rep(i, n - 1) {
        {
            ll left = i + 1, right = n+1;
            while (right - left > 1) {
                ll m = left + right;
                m /= 2;
                auto s = tree.prod(i, m);
                //cout << s.ok() << ":" << i << "," << m << "," << s.v1;
                //cout << "," << s.v2 << "," << s.m << endl;
                if (s.ok()) {
                    left = m;
                }
                else {
                    right = m;
                }
            }
            sum += left - i - 1;
        }
    }
    cout << sum << endl;

	return 0;
}