#include <bits/stdc++.h>
#define show(x) std::cerr << #x << " = " << x << std::endl
using ll = long long;
using ull = unsigned long long;
using ld = long double;
constexpr ll MOD = 1000000007LL;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 10;
std::mt19937 mt{std::random_device{}()};
constexpr std::size_t PC(const ull v)
{
    ull count = (v & 0x5555555555555555ULL) + ((v >> 1) & 0x5555555555555555ULL);
    count = (count & 0x3333333333333333ULL) + ((count >> 2) & 0x3333333333333333ULL);
    count = (count & 0x0f0f0f0f0f0f0f0fULL) + ((count >> 4) & 0x0f0f0f0f0f0f0f0fULL);
    count = (count & 0x00ff00ff00ff00ffULL) + ((count >> 8) & 0x00ff00ff00ff00ffULL);
    count = (count & 0x0000ffff0000ffffULL) + ((count >> 16) & 0x0000ffff0000ffffULL);
    return static_cast<std::size_t>((count & 0x00000000ffffffffULL) + ((count >> 32) & 0x00000000ffffffffULL));
}
constexpr std::size_t LG(ull v) { return v == 0 ? 0 : (v--, v |= (v >> 1), v |= (v >> 2), v |= (v >> 4), v |= (v >> 8), v |= (v >> 16), v |= (v >> 32), PC(v)); }
constexpr ull SZ(const ull v) { return 1ULL << LG(v); }

template <typename Base>
class BinaryIndexedTree
{
public:
    using T = typename Base::T;
    using AbelGroup = Base;
    BinaryIndexedTree(const std::size_t n) : data_num(n), size(SZ(n)), value(size + 1, Base::id()) {}
    template <typename InIt>
    BinaryIndexedTree(const InIt first, const InIt last) : data_num(distance(first, last)), size(SZ(data_num)), value(size + 1, Base::id())
    {
        copy(first, last, value.begin() + 1);
        for (std::size_t x = 1; x < size; x++) { value[x + (x & -x)] = op(value[x + (x & -x)], value[x]); }
    }
    T accumulate(const std::size_t a) const  // [0,a]
    {
        T sum = Base::id();
        for (std::size_t ind = a + 1; ind != 0; ind &= ind - 1) { sum = op(sum, value[ind]); }
        return sum;
    }
    void add(const std::size_t a, const T& val)
    {
        for (std::size_t ind = a + 1; ind <= size; ind += ind & (-ind)) { value[ind] = op(value[ind], val); }
    }

private:
    const std::size_t data_num, size;
    const Base op{};
    std::vector<T> value;
};
struct Sum
{
    using T = ll;
    T operator()(const T& a, const T& b) const { return a + b; }
    static T inv(const T& a) { return -a; }
    static constexpr T id() { return 0; }
};
int main()
{
    int N;
    std::cin >> N;
    std::vector<int> M(N);
    for (int i = 0; i < N; i++) { std::cin >> M[i]; }
    BinaryIndexedTree<Sum> bit(N + 1);
    int ans = 0;
    for (int i = N - 1; i >= 0; i--) {
        ans += bit.accumulate(M[i]);
        bit.add(M[i], 1);
    }
    std::cout << ans << std::endl;
    return 0;
}