#line 1 "/home/siro53/kyo-pro/compro_library/template/template.cpp"
#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#ifndef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) { os << ','; }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
    }
} __Setup;

using ll = long long;
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define FOR(i, a, b) for(int i = (a); i < int(b); i++)
#define REP(i, n) FOR(i, 0, n)
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
constexpr int MOD = 1000000007;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

//-------------------------------------
#line 2 "c.cpp"

#include <atcoder/segtree>

const int inf = 1 << 29;

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

S e() {
    return S{inf, inf, -inf};
}

S op(S a, S b) {
    int M = max(a.M, b.M);
    int m1, m2;
    if(a.m1 < b.m1) {
        m1 = a.m1;
        m2 = min({a.m2, b.m1, b.m2});
    }else{
        m1 = b.m1;
        m2 = min({b.m2, a.m1, a.m2});
    }
    return S{m1, m2, M};
}

bool f(S x) {
    return (x.m1 + x.m2 >= x.M);
} 

int main(){
    int N; cin >> N;
    atcoder::segtree<S, op, e> seg(N);
    REP(i, N) {
        int a; cin >> a;
        seg.set(i, S{a, inf, a});
    }

    ll ans = 0;
    
    REP(l, N-1) {
        int r = seg.max_right<f>(l);
        ans += r - l - 1;
    }

    cout << ans << "\n";
}