#include<iostream>
using namespace std;
const int N=500010;
typedef long long ll;
ll cnt;
int n,a[N],num[N];
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
void sort(int l,int r,int *a)
{
if(l>=r) return ;
int mid= l+r >> 1;
sort(l,mid,a);
sort(mid+1,r,a);
int pl=l,pr=mid+1,temp=l;
while(pl<=mid&&pr<=r)
{
if(a[pl]<=a[pr]) num[temp++]=a[pl++];
else num[temp++]=a[pr++],cnt+=mid-pl+1;
}
while(pr<=r) num[temp++]=a[pr++];
while(pl<=mid) num[temp++]=a[pl++];
for(int i=l;i<=r;i++) a[i]=num[i];
return ;
}
int main()
{
IOS;
cin>>n;
for(int i=0;i<n;i++) cin>>a[i];
sort(0,n-1,a);
cout<<cnt;
return 0;
}