fn run<'a, I: Iterator<Item = &'a str>>(mut scanner: I) {
    macro_rules! scan {
        ([$t:tt; $n:expr]) => ((0..$n).map(|_| scan!($t)).collect::<Vec<_>>());
        ($t:ty) => (scanner.next().unwrap().parse::<$t>().unwrap());
    }
    macro_rules! input {
        ($($($v:ident)* : $t:tt),* $(,)?) => ($(let $($v)* = scan!($t);)*);
    }
    
    input! {
        n: usize,
        a: [u32; n],
    }

    let mut one = 0;
    let mut two = 0;
    for a in a {
        match a {
            1 => one += 1,
            2 => two += 1,
            _ => (),
        }
    }

    let mut ans: u64 = (n * (n - 1)) as u64 / 2;
    ans += one * (one - 1) / 2;
    ans += one * (n as u64 - one - two);
    ans += one * two * 2;
    println!("{}", ans);
}

fn main() {
    let ref mut buf = Vec::new();
    std::io::Read::read_to_end(&mut std::io::stdin(), buf).ok();
    run(std::str::from_utf8(buf).unwrap().split_whitespace());
}