#[macro_export]
macro_rules! setup {
    { mut $input:ident: SplitWhitespace $(,)? } => {
        use std::io::Read;
        let mut buf = String::new();
        std::io::stdin().read_to_string(&mut buf).ok();
        let mut $input = buf.split_whitespace();
    };
}

#[macro_export]
macro_rules! parse_next {
    ($str_iter:expr) => {
        $str_iter.next().unwrap().parse().ok().unwrap()
    };
}

fn main() {
    setup! { mut input: SplitWhitespace };

    let n: usize = parse_next!(input);
    let a: Vec<usize> = (0..n).map(|_| parse_next!(input)).collect();

    let zeros = a
        .iter()
        .enumerate()
        .filter(|(_, x)| **x == 0)
        .map(|(i, _)| i)
        .collect::<Vec<_>>();

    let ans = (|| {
        (0..n).fold(0, |acc, l| match a[l] == 0 {
            true => acc + (n - l),
            false => match zeros.iter().filter(|i| **i >= l).nth(0) {
                Some(i) => acc + (n - i),
                None => acc,
            },
        })
    })();

    println!("{}", ans);
}