#include <iostream>
#include <fstream>

using namespace std;

int mergesort(int a[], int first, int last, int n);
int merge(int a[], int first, int m, int last, int n);

int main() {
    ifstream fin("input.txt");
    ofstream fout("output.txt");
    int n;
    fin >> n;
    int *a = new int [n];
    for(int i = 0; i < n; i++){
        fin >> a[i];
    }
    fout << mergesort(a, 0, n - 1, n);
    return 0;
}

int merge(int a[], int first, int m, int last, int n){
   int amt = 0;
   int l = first;
   int r = last;
   int k = first;
   int *b = new int [n];
   while ((l <= m - 1) && (r <= last)){
       if (a[l] <= a[r]){
           b[k] = a[l];
           k++;
           l++;
       }
       else{
           b[k] = a[r];
           k++;
           r++;
           amt = amt + (m - l);
       }
   }
    while (l <= m - 1) {
        b[k] = a[l];
        k++;
        l++;
    }
    while (r <= last) {
        b[k] = a[r];
        k++;
        r++;
    }
    for(int i = 0; i < last; i++){
        a[i] = b[i];
    }
    return amt;
}

int mergesort(int a[], int first, int last, int n){
   int m = (first + last)/2;
   int amt = 0;
   if (first < last){
       amt  = mergesort(a, first, m, n);
       amt += mergesort(a, m + 1, last, n);
       amt += merge(a, first, m + 1, last, n);
   }
    return amt;
}