#include<bits/stdc++.h>
using namespace std;
vector<int> tree[1 << 17];
int M = 1, liczba_inwersji = 0;
void f(int v){ //merge sort
  int lw = 0, pw = 0, n = tree[2 * v].size();
  while(lw < n || pw < n){
    if(lw < n && tree[v * 2][lw] <= tree[v * 2 + 1][pw])
      tree[v].push_back(tree[v * 2][lw++]);
    else{
      tree[v].push_back(tree[v * 2 + 1][pw++]);
      liczba_inwersji += n - lw;
    }
  }
}
int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  while(M < n) M *= 2;
  for(int i = M, a;i < n + M;i++){
    cin >> a;
    tree[i].push_back(a);
  }
  for(int i = n + M;i < 2 * M;i++)
    tree[i].push_back(INT_MAX);
  for(int i = M - 1;i > 0;i--)
    f(i);
  cout << liczba_inwersji;
}