#include <iostream>
#include <vector>

using std::vector;
using std::swap;

long long get_number_of_inversions(vector<int> &a, vector<int> &b, size_t left, size_t right)
{
    long long number_of_inversions = 0;
    if (right <= left + 1) return number_of_inversions;
    size_t ave = left + (right - left) / 2;
    number_of_inversions += get_number_of_inversions(a, b, left, ave);
    number_of_inversions += get_number_of_inversions(a, b, ave, right);

    size_t i = left, j = ave, k = left;

    while ((i != ave) && (j != right)) {
        if (a[i] <= a[j]) {
            b[k] = a[i];
            i++;

        } else {
            b[k] = a[j];
            j++;
            number_of_inversions += (ave - i);
        }
        k++;
    }

    for( ; i != ave; i++, k++)
        b[k] = a[i];

    for( ; j != right; j++, k++)
        b[k] = a[j];

    for(i = left, k = left; i < right; i++, k++)
        a[i] = b[k];

    return number_of_inversions;
}

int main() {
  int n;
  std::cin >> n;
  vector<int> a(n);
  for (size_t i = 0; i < a.size(); i++) {
    std::cin >> a[i];
  }
  vector<int> b(a.size());
  std::cout << get_number_of_inversions(a, b, 0, a.size()) << '\n';
}