fn calc(index: usize, parents: &Vec<usize>) -> usize {
    parents.iter().filter(|&p| *p < index).count()
}

fn dfs(index: usize, children: &mut Vec<Vec<usize>>, parents: &mut Vec<usize>, result: &mut usize) {
    if children[index].is_empty() { *result += calc(index, parents); }
    while let Some(child) = children[index].pop() {
        parents.push(index);
        dfs(child, children, parents, result);
        parents.pop();
        *result += calc(index, parents);
    }
}

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let mut children: Vec<Vec<usize>> = vec![vec![]; n];
    a.trim().split_whitespace().map(|s| s.parse::<usize>().unwrap()).enumerate().for_each(|pair| {
        let current = pair.0 + 1;
        children[pair.1].push(current);
    });

    let mut result: usize = 0;
    let mut parents: Vec<usize> = vec![];
    dfs(0, &mut children, &mut parents, &mut result);
    println!("{}", result);
}