#![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 a = read_vec::<usize>();

    if n == 1 {
        println!("0");
        return;
    }

    let mut from_right = vec![0; n];
    from_right[n - 2] = 1;
    for i in (0..n - 2).rev() {
        if a[i] != a[i + 1] {
            from_right[i] = from_right[i + 1] + 1;
        } else {
            from_right[i] = 1;
        }
    }
    debug!(from_right);

    let mut ans = 0i64;
    for i in 0..n {
        if a[i] == 1 {
            ans += from_right[i];
        }
    }
    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()
}