/////
include[HTML_REMOVED]
using namespace std;
const int N=100010;
int n,a[N],tmp[N];
long long merge_sort(int a[],int l,int r)
{
if(l==r) return 0;
int mid=(l+r)/2;
long long res=merge_sort(a,l,mid)+merge_sort(a,mid+1,r);
//res+=merge_sort(a,mid+1,r);
int k=0,i=l,j=mid+1;
while(i<=mid&&j<=r)
{
if(a[i]<=a[j]) tmp[k++]=a[i++];
else {
tmp[k++]=a[j++];
res+=mid-i+1;
}
}
while(i<=mid) tmp[k++]=a[i++];
while(j<=r) tmp[k++]=a[j++];
for(i=l,j=0;i<=r;i++,j++) a[i]=tmp[j];
return res;
}
int main()
{
cin>>n;
for(int i=0;i[HTML_REMOVED]>a[i];
//暴力解 n^2–时间超过
/for(int i=0;i<n-1;i)
{
for(int j=i+1;j<n;j)
{
if(a[j]<a[i]) sum++;
}
}/
cout<<merge_sort(a,0,n-1);
return 0;
}