#include <bits/stdc++.h>

using i32 = std::int32_t;
using u32 = std::uint32_t;
using i64 = std::int64_t;
using u64 = std::uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

class rep {
    struct Iter {
        usize itr;
        constexpr Iter(const usize pos) noexcept : itr(pos) {}
        constexpr void operator++() noexcept { ++itr; }
        constexpr bool operator!=(const Iter& other) const noexcept {
            return itr != other.itr;
        }
        constexpr usize operator*() const noexcept { return itr; }
    };
    const Iter first, last;

  public:
    explicit constexpr rep(const usize first, const usize last) noexcept
        : first(first), last(std::max(first, last)) {}
    constexpr Iter begin() const noexcept { return first; }
    constexpr Iter end() const noexcept { return last; }
};

template <class T> using Vec = std::vector<T>;

void B_main() {
    usize N;
    std::cin >> N;
    Vec<u32> A(N);
    usize one = 0, two = 0;
    for (auto& x : A) {
        std::cin >> x;
        if (x == 1) one += 1;
        if (x == 2) two += 1;
    }
    std::cout << 2 * (u64)one * (one - 1) / 2 + 2 * (u64)one * (N - one - two) +
                     3 * (u64)one * two + 1 * (u64)(N - one) * (N - one - 1) / 2
              << '\n';
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    B_main();
    return 0;
}