// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

use std::convert::From;

pub trait Monoid {
    type T: Clone + PartialEq;

    const UNIT: Self::T;

    fn merge(x: &Self::T, y: &Self::T) -> Self::T;
    fn apply(target: &Self::T, x: Self::T) -> Self::T;
}

#[derive(Debug, PartialEq)]
pub struct SegmentTree<M: Monoid> {
    n: usize,
    data: Vec<M::T>,
}

impl<M: Monoid> SegmentTree<M> {
    pub fn new(size: usize) -> Self {
        Self::with_initial_value(size, M::UNIT)
    }

    pub fn with_initial_value(size: usize, initial_value: M::T) -> Self {
        let mut n : usize = 1;
        while n < size {
            n <<= 1;
        }

        let mut data = vec![initial_value.clone(); 2 * n - 1];

        if initial_value != M::UNIT {
            for i in (0..(n-1)).rev() {
                data[i] = M::merge(&data[i * 2 + 1], &data[i * 2 + 2]);
            }
        }

        SegmentTree { n, data }
    }
}

impl<M: Monoid> From<&[M::T]> for SegmentTree<M> {
    fn from(v: &[M::T]) -> Self {
        let mut st = SegmentTree::new(v.len());

        for i in 0..v.len() {
            st.data[i + st.n - 1] = v[i].clone();
        }

        for i in (0..(st.n-1)).rev() {
            st.data[i] = M::merge(&st.data[i * 2 + 1], &st.data[i * 2 + 2]);
        }

        st
    }
}

impl<M: Monoid> SegmentTree<M> {
    pub fn update(&mut self, idx: usize, val: M::T) {
        let mut idx = idx + self.n - 1;
        self.data[idx] = M::apply(&self.data[idx], val);

        while idx > 0 {
            idx = (idx - 1) / 2;
            self.data[idx] = M::merge(&self.data[idx * 2 + 1], &self.data[idx * 2 + 2]);
        }
    }

    pub fn query(&self, begin: usize, end: usize) -> M::T {
        self._query(begin, end, 0, 0, self.n)
    }

    fn _query(&self, begin: usize, end: usize, k: usize, l: usize, r: usize) -> M::T {
        if r <= begin || end <= l {
            return M::UNIT;
        }

        if begin <= l && r <= end {
            return self.data[k].clone();
        }

        let vl = self._query(begin, end, k * 2 + 1, l, (l + r) / 2);
        let vr = self._query(begin, end, k * 2 + 2, (l + r) / 2, r);
        M::merge(&vl, &vr)
    }
}

#[derive(Debug, PartialEq)]
struct RangeMin;
impl Monoid for RangeMin {
    type T = i64;

    const UNIT : Self::T = std::i64::MAX;

    fn merge(x: &Self::T, y: &Self::T) -> Self::T {
        x + y
    }

    fn apply(vm: &Self::T, vo: Self::T) -> Self::T {
        vm + vo
    }
}

#[derive(Debug, PartialEq)]
struct RangeSum;
impl Monoid for RangeSum {
    type T = i64;

    const UNIT : Self::T = 0;

    fn merge(x: &Self::T, y: &Self::T) -> Self::T {
        x + y
    }

    fn apply(vm: &Self::T, vo: Self::T) -> Self::T {
        vm + vo
    }
}

fn solve(cur: usize, g: &Vec<Vec<usize>>, ans: &mut i64, st: &mut SegmentTree<RangeSum>) {
    *ans += st.query(0, cur + 1);
    st.update(cur, 1);
    for &nex in g[cur].iter() {
        solve(nex, g, ans, st);
    }
    st.update(cur, -1);
}

fn main() {
    input! {
        n: usize,
        a: [usize; n - 1],
    }

    let mut g : Vec<Vec<usize>> = vec![vec![]; n];
    for (i, &j) in a.iter().enumerate() {
        g[j].push(i + 1);
    }

    let mut ans : i64 = 0;
    let mut st = SegmentTree::<RangeSum>::new(n);
    solve(0, &g, &mut ans, &mut st);
    println!("{}", ans);
}