#include <bits/stdc++.h>
using namespace std;

using i64 = int64_t;

#define rep(i, x, y) for (i64 i = i64(x), i##_max_for_repmacro = i64(y); i < i##_max_for_repmacro; ++i)
#define debug(x) #x << "=" << (x)

#ifdef DEBUG
#define _GLIBCXX_DEBUG
#define print(x) std::cerr << debug(x) << " (L:" << __LINE__ << ")" << std::endl
#else
#define print(x)
#endif

template <i64 p>
class fp {
    public:
    i64 x;
    fp() : x(0) {}
    fp(i64 x_) : x((x_ % p + p) % p) {}
    fp operator+() const { return fp(x); }
    fp operator-() const { return fp(-x); }
    fp& operator+=(const fp& y) {
        x += y.x;
        if (x >= p) x -= p;
        return *this;
    }
    fp& operator-=(const fp& y) { return *this += -y; }
    fp& operator*=(const fp& y) {
        x = x * y.x % p;
        return *this;
    }
    fp& operator/=(const fp& y) { return *this *= fp(inverse(y.x)); }
    fp operator+(const fp& y) const { return fp(x) += y; }
    fp operator-(const fp& y) const { return fp(x) -= y; }
    fp operator*(const fp& y) const { return fp(x) *= y; }
    fp operator/(const fp& y) const { return fp(x) /= y; }
    bool operator==(const fp& y) const { return x == y.x; }
    bool operator!=(const fp& y) const { return !(*this == y); }
    i64 extgcd(i64 a, i64 b, i64& x, i64& y) {
        i64 d = a;
        if (b != 0) {
            d = extgcd(b, a % b, y, x);
            y -= (a / b) * x;
        } else {
            x = 1;
            y = 0;
        }
        return d;
    }
    i64 inverse(i64 a) {
        i64 x, y;
        extgcd(a, p, x, y);
        return (x % p + p) % p;
    }
};

template <i64 p>
i64 abs(const fp<p>& x) { return x.x; }

template <i64 p>
istream& operator>>(istream& is, fp<p>& x) {
    is >> x.x;
    return is;
}

template <i64 p>
ostream& operator<<(ostream& os, const fp<p>& x) {
    os << x.x;
    return os;
}

template <typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << ", " << p.second << ")";
    return os;
}

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& vec) {
    os << "[";
    for (const auto& v : vec) {
        os << v << ",";
    }
    os << "]";
    return os;
}

template <typename T>
bool chmin(T& a, const T& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <typename A, typename T, size_t size>
void fill(A (&ary)[size], const T& val) {
    fill((T*)ary, (T*)(ary + size), val);
}

constexpr int inf = 1.01e9;
constexpr i64 inf64 = 4.01e18;
constexpr long double eps = 1e-9;

// double(64bit浮動小数)のn分探索のループ回数の上限(2分探索なら50でも十分かもしれない). long double(80ビットの x87 浮動小数点型?)だと, 2分探索であってもこれだと足りないケースがある気がするので, もうちょっと余裕を持たせた方が良さそう.
constexpr i64 max_loop = 100;

template <typename T, typename F>
class segtree {
    F op;
    T id;
    i64 n, size_;
    vector<T> dat;

public:
    segtree() = default;
    segtree(F op, T id, i64 size, T initial_value) : op(op), id(id) { init(size, initial_value); }
    void init(int size, T initial_value) {
        size_ = size;
        n = 1;
        while (n < size) n *= 2;
        dat.assign(2 * n - 1, id);

        rep(i, n - 1, n - 1 + size_) dat[i] = initial_value;
        for (i64 i = n - 2; i >= 0; --i) dat[i] = op(dat[i * 2 + 1], dat[i * 2 + 2]);
    }
    int size() const { return size_; }
    void update(i64 k, T a) {
        k += n - 1;  // leaf
        dat[k] = a;
        while (k > 0) {
            k = (k - 1) / 2;
            dat[k] = op(dat[k * 2 + 1], dat[k * 2 + 2]);
        }
    }
    T at(int index) { return dat[index + n - 1]; }
    void add(i64 k, T a) { update(k, at(k) + a); }
    T query(i64 l, i64 r) {
        l += n - 1;
        r += n - 1;
        T res_l = id, res_r = id;
        while (l < r) {
            if ((l & 1) == 0) {
                res_l = op(res_l, dat[l]);
                ++l;
            }
            if ((r & 1) == 0) {
                res_r = op(dat[r - 1], res_r);
                --r;
            }
            l = (l - 1) / 2;
            r = (r - 1) / 2;
        }
        return op(res_l, res_r);
    }
};

template <typename T>
pair<vector<T>, map<T, T>> compress(const vector<T>& xs) {
    vector<T> unzip;
    unzip.reserve(xs.size());
    for (const auto& x : xs) unzip.emplace_back(x);

    sort(begin(unzip), end(unzip));
    unzip.erase(unique(begin(unzip), end(unzip)), end(unzip));

    map<T, i64> zip;
    rep(i, 0, unzip.size()) zip[unzip[i]] = i;

    return make_pair(unzip, zip);
}

void solve() {
    //constexpr i64 mod = 1'000'000'007;
    i64 n;
    cin >> n;
    vector<i64> a(n);
    rep(i,0,n) cin >> a[i];

    vector<i64> unzip;
    map<i64,i64> zip;
    tie(unzip,zip)=compress(a);

    auto add=[](i64 a,i64 b){ return a+b; };
    segtree<i64,decltype(add)> seg(add,0,n,0);

    i64 ans=0;
    rep(i,0,n){
        i64 zi=zip[a[i]];
        ans+=seg.query(zi,n);
        seg.update(zi,1);
    }

    cout << ans << endl;
}

int main() {
    std::cin.tie(0);
    std::ios::sync_with_stdio(false);
    cout.setf(ios::fixed);
    cout.precision(16);
    solve();
    return 0;
}



Measured memory_bytes: 32632