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

signed main() {
  ios::sync_with_stdio(false);
  
  int N;
  cin >> N;
  
  vector<int> M(N);
  for (int i = 0; i < N; ++i) cin >> M[i];
  
  vector<int> dat(N + 1);
  auto add = [&](int x, int v) {
    for (int i = x; i < dat.size(); i += i & -i) dat[i] += v;
  };
  auto sum = [&](int x) {
    int res = 0;
    for (int i = x; i; i -= i & -i) res += dat[i];
    return res;
  };
  
  int ans = 0;
  for (int i = 0; i < N; ++i) {
    ans += sum(N) - sum(M[i]);
    add(M[i], 1);
  }
  
  cout << ans << endl;
}