#![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::<i64>();
    let ones = a.iter().filter(|&&x| x == 1).count() as i64;
    let twos = a.iter().filter(|&&x| x == 2).count() as i64;
    let others = n as i64 - ones - twos;
    let mut ans = 0;
    // 1 - 1
    ans += 2 * (ones * (ones - 1) / 2);
    // 1 - 2
    ans += 3 * ones * twos;
    // 1 - other
    ans += 2 * ones * others;

    ans += (twos + others) * (twos + others - 1) / 2;
    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()
}