#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
const int N=1e5+10;
int a[N];
int ans=0;
int tmp[N];
void mergesort(int a[],int l,int r)
{
if(l>=r)return;
int mid=l+r>>1;
mergesort(a,l,mid);
mergesort(a,mid+1,r);
int i=l,j=mid+1;
int k=0;
while(i<=mid&&j<=r)
{
if(a[i]<=a[j])
{
tmp[k++]=a[i++];
}
else
{
tmp[k++]=a[j++];
ans+=mid-i+1;//与i后面的数均构成逆序，个数mid-i+1
}
}
while(i<=mid)tmp[k++]=a[i++];
while(j<=r)tmp[k++]=a[j++];
for(int i=l,j=0;i<=r;i++,j++)a[i]=tmp[j];
}
int main()
{
int n;
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>a[i];
}
mergesort(a,1,n);
// for(int i=1;i<=n;i++)cout<<a[i]<<' ';
cout<<ans<<endl;
return 0;