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

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl

//http://www.prefield.com/algorithm/sort/mergecount.html
// しかし配列コピーのコストが高い？
int mergecount(vector<ll> &a) {
  int count = 0;
  int n = a.size();
  if (n > 1) {
    vector<ll> b(a.begin(), a.begin() + n/2);
    vector<ll> c(a.begin() + n/2, a.end());
    count += mergecount(b);
    count += mergecount(c);
    for (int i = 0, j = 0, k = 0; i < n; ++i)
      if (k == c.size())       a[i] = b[j++];
      else if (j == b.size())  a[i] = c[k++];
      else if (b[j] <= c[k])   a[i] = b[j++];
      else                   { a[i] = c[k++]; count += n/2 - j; }
  }
  return count;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N;
    cin >> N;

    vector<ll> A(N);
    FOR(i, 0, N){
        cin >> A.at(i);
    }

    ll ans = mergecount(A);    
    p(ans);
    
    return 0;
}