#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=100010;
int a[N],p[N];

int merge_sort(int l,int r)
{
    if(l>=r) return 0;
    int mid=(l+r)/2;
    int res=(merge_sort(l,mid)+merge_sort(mid+1,r));
    int i=l,j=mid+1,k=0;
    while(i<=mid&&j<=r)
    {
        if(a[i]<=a[j]) p[k++]=a[i++];
        else p[k++]=a[j++],res+=mid-i+1;
    }
    while(i<=mid) p[k++]=a[i++];
    while(j<=r) p[k++]=a[j++];
    for(i=l,j=0;i<=r;i++,j++)
    a[i]=p[j];
    return res;
}

signed main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)
    cin>>a[i];
    cout<<merge_sort(1,n);
    return 0;
}