include [HTML_REMOVED]
using namespace std;
typedef long long LL;
const int N = 100100;
int a[N],temp[N],res;
LL qs(int l,int r)
{
if(l>=r)return 0;
int mid=r+l>>1;
LL res=qs(l,mid)+qs(mid+1,r);
int i=l,j=mid+1,k=0;
while(i<=mid&&j<=r)
if(a[i]<=a[j])temp[k++]=a[i++];
else
{
temp[k++]=a[j++];
res+=mid-i+1;
}
while(i<=mid)temp[k++]=a[i++];
while(j<=r)temp[k++]=a[j++];
for(i=l,j=0;i<=r;j++,i++)a[i]=temp[j];
return res;
}
int main()
{
int x;
cin>>x;
for(int i=0;i[HTML_REMOVED]>a[i];
cout<<qs(0,x-1);
return 0;
}