#include <bits/stdc++.h>
using namespace std;
const int N = 1e8;
long long q[N];
long long ans = 0;
long long tmp[N];
void merge_sort(long long q[], int l, int r)
{
    if(l >= r)
        return;
    int mid = l + r >> 1;
    merge_sort(q, l, mid);
    merge_sort(q, mid + 1, r);
    int k=0,i=l,j=mid+1;
    while(i<=mid&&j<=r)
    {
        if(q[i]<=q[j])tmp[k++]=q[i++];
        else
        {
            tmp[k++]=q[j++];
            ans+=mid+1-i;//关键
        }
    }
    while(i<=mid)tmp[k++]=q[i++];
    while(j<=r)tmp[k++]=q[j++];
    for(i=l,j=0;i<=r;i++,j++)
    {
        q[i]=tmp[j];
    }

}
int main()
{
    int n, i;
    scanf("%d", &n);
    for(i = 0; i < n; i++)
    {
        scanf("%d", &q[i]);
    }
    merge_sort(q, 0, n - 1);
    printf("%lld", ans);
    return 0;
}