#![allow(unused_imports)]
use std::cmp::*;
use std::collections::*;
use std::io::Write;
use std::ops::Bound::*;

#[allow(unused_macros)]
macro_rules! debug {
    ($($e:expr),*) => {
        #[cfg(debug_assertions)]
        $({
            let (e, mut err) = (stringify!($e), std::io::stderr());
            writeln!(err, "{} = {:?}", e, $e).unwrap()
        })*
    };
}

fn main() {
    let n = read::<usize>();
    let mut ans = 0i64;
    let mut a = read_vec::<i64>();

    for ti in 0..2 {
        let mut aa = a
            .iter()
            .enumerate()
            .map(|(i, &x)| (x, i))
            .collect::<Vec<_>>();

        if ti == 0 {
            aa.sort_by_key(|&(x, i)| (x, Reverse(i)));
        } else {
            aa.sort();
        }
        let mut seg = SegTree::new(n, 0i64, max);
        for i in 0..n {
            seg.update(i, a[i]);
        }

        let mut poses = BTreeSet::new();
        for (m2, i) in aa {
            poses.insert(i);
            let r_iter = poses.range((Unbounded, Excluded(i)));
            let r;
            if let Some(x) = r_iter.rev().next() {
                r = x + 1;
            } else {
                r = 0;
            }

            let mut l_iter = poses.range((Excluded(i), Unbounded));
            let mut l = 0;
            if let Some(x) = l_iter.next() {
                l = *x;
            } else {
                continue;
            }
            let m1 = a[l];
            let ll;
            if let Some(x) = l_iter.next() {
                ll = x - 1;
            } else {
                ll = n - 1;
            }
            // debug!((m2, r, l, ll));
            let m = seg.query(i, l + 1);
            if m > m1 + m2 {
                continue;
            }
            let lld;
            if seg.query(i, ll + 1) <= m1 + m2 {
                lld = ll;
            } else {
                let (ok, _) = binary_search(i, ll, |mid| seg.query(i, mid + 1) <= m1 + m2);
                lld = ok;
            }
            let mut rd = i;
            for j in (r..i).rev() {
                let m = seg.query(j, i + 1);
                if m > m1 + m2 {
                    continue;
                }
                rd = j;
            }
            let temp = (lld - l + 1) as i64 * (i - rd + 1) as i64;
            // debug!((i, lld, rd, temp));
            ans += temp;
        }
        a.reverse();
    }
    println!("{}", ans);
}

type Input = usize;
fn binary_search<F>(lb: Input, ub: Input, criterion: F) -> (Input, Input)
where
    F: Fn(Input) -> bool,
{
    assert_eq!(criterion(lb), true);
    assert_eq!(criterion(ub), false);
    let mut ok = lb;
    let mut ng = ub;
    while ng - ok > 1 {
        let mid = (ng + ok) / 2;
        if criterion(mid) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    (ok, ng)
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

#[derive(Clone)]
struct SegTree<T, F>
where
    F: Fn(T, T) -> T,
    T: std::clone::Clone + std::marker::Copy,
{
    n: usize,
    dat: Vec<T>,
    init: T,
    functor: F,
}

impl<T, F> SegTree<T, F>
where
    F: Fn(T, T) -> T,
    T: std::clone::Clone + std::marker::Copy,
{
    fn new(n: usize, init: T, f: F) -> SegTree<T, F> {
        let mut m = 1;
        // For simplicity, we use 2 ** n sized SegTree.
        while m < n {
            m *= 2;
        }
        SegTree {
            n: m,
            dat: vec![init; 2 * m - 1],
            init: init,
            functor: f,
        }
    }

    // dat[k] = a;
    fn update(&mut self, k: usize, a: T) {
        let mut k = k;
        k += self.n - 1;
        self.dat[k] = a;
        while k > 0 {
            k = (k - 1) / 2;
            self.dat[k] = (self.functor)(self.dat[k * 2 + 1], self.dat[k * 2 + 2]);
        }
    }

    // [a, b)
    fn query(&self, a: usize, b: usize) -> T {
        self.query_inner(a, b, 0, 0, self.n)
    }

    fn query_inner(&self, a: usize, b: usize, k: usize, l: usize, r: usize) -> T {
        if r <= a || b <= l {
            return self.init;
        }
        if a <= l && r <= b {
            return self.dat[k];
        }

        let vl = self.query_inner(a, b, k * 2 + 1, l, (l + r) / 2);
        let vr = self.query_inner(a, b, k * 2 + 2, (l + r) / 2, r);
        (self.functor)(vl, vr)
    }
}