//H
#include <algorithm>
#include <fstream>
#include <iostream>
#include <vector>

using namespace std;

long long int merge(vector<int> &main_vec, int l, int r) {
  int m = (l + r) / 2;
  int i = l;
  int j = m + 1;
  int k = 0;
  vector<int> C(r - l + 1);
  long long int count = 0;

  while ((i <= m) && (j <= r)) {
    if (main_vec[i] <= main_vec[j]) {
      C[k++] = main_vec[i++];
    } else {
      C[k++] = main_vec[j++];
      count = count + m - i + 1;
    }
  }

  while (i <= m) C[k++] = main_vec[i++];

  while (j <= r) C[k++] = main_vec[j++];

  for (int d = 0; d < r - l + 1; d++) main_vec[d + l] = C[d];

  return count;
}

long long int msort(vector<int> &main_vec, int l, int r) {
  if (l >= r) return 0;
  int m = (l + r) / 2;

  long long int count = msort(main_vec, l, m);
  count += msort(main_vec, m + 1, r);
  count += merge(main_vec, l, r);

  return count;
}

int main() {
  ifstream input("input.txt");
  int n;
  input >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) {
    input >> a[i];
  }

  long long int count = msort(a, 0, n - 1);
  ofstream output("output.txt");
  output << count;
  return 0;
}