fn dfs(cur: usize, parent: usize, edges: &Vec<Vec<usize>>, tour: &mut Vec<usize>) {
    tour.push(cur);
    for &to in edges[cur].iter().filter(|&&x| x != parent) {
        dfs(to, cur, edges, tour);
    }
    tour.push(cur);
}

fn main() {
    let n = read::<usize>();
    let a = read_vec::<usize>();
    let mut seg = SegTree::new(2 * n, 0i64, |x, y| x + y);

    let mut edges = vec![vec![]; n];
    for i in 0..n - 1 {
        edges[i + 1].push(a[i]);
        edges[a[i]].push(i + 1);
    }
    let mut tour = vec![];
    dfs(0, 0, &edges, &mut tour);
    let mut pre_order = vec![0; n];
    let mut post_order = vec![0; n];
    for i in (0..tour.len()).rev() {
        pre_order[tour[i]] = i;
    }
    for i in 0..tour.len() {
        post_order[tour[i]] = i;
    }
    let mut ans = 0;
    for i in (0..n).rev() {
        ans += seg.query(pre_order[i], post_order[i] + 1);
        seg.update(pre_order[i], 1);
    }
    println!("{}", ans);
}

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)
    }
}