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

struct fenwick_tree {
    typedef int T;
    T n;
    vector<T> bit;

    // 各要素の初期値は 0
    fenwick_tree(T num) : bit(num+1, 0) { n = num; }

    // a_i += w
    void add(T i, T w) {
        for (T x = i; x <= n; x += x & -x) {
            bit[x] += w;
        }
    }
    // [1, i] の和を計算.
    T sum(T i) {
        T ret = 0;
        for (T x = i; x > 0; x -= x & -x) {
            ret += bit[x];
        }
        return ret;
    }
    // [left+1, right] の和を計算.
    T sum(T left, T right) {
        return sum(right) - sum(left);
    }
};

int main() {
  int n;
  cin >> n;
  vector<int> p(n);
  int ans = 0;
  for (int i = 0; i < n; i++) cin >> p[i];
  fenwick_tree f_tree(n);

  for (int j = 0; j < n; j++) {
    ans += j - f_tree.sum(p[j]);
    f_tree.add(p[j], 1);
  }

  cout << ans << endl;
}