fn main() {
    let ref mut buf = String::new();
    std::io::Read::read_to_string(&mut std::io::stdin(), buf).ok();
    let mut iter = buf.split_whitespace();

    macro_rules! scan {
        ([$t:tt; $n:expr]) => ((0..$n).map(|_| scan!($t)).collect::<Vec<_>>());
        (($($t:tt),*)) => (($(scan!($t)),*));
        (Usize1) => (scan!(usize) - 1);
        (Bytes) => (scan!(String).into_bytes());
        ($t:ty) => (iter.next().unwrap().parse::<$t>().unwrap());
    }

    let n = scan!(usize);
    let a = scan!([u8; n]);

    let mut ans = n * (n - 1) / 2;
    let mut one = 0;
    for a in a {
        if a == 1 {
            ans -= one;
            one += 1;
        } else {
            ans += 1;
            one = 0;
        }
    }
    println!("{}", ans);
}