#include<iostream>
using namespace std;
long long n,a[500005],d[500005],ans=0;
void merge(int s,int t){
	if(s==t)return;
	int mid=(s+t)/2,i=s,j=mid+1,k=s;
	merge(s,mid);
	merge(mid+1,t);
	for(i=s;i<=mid;i++){
		while((a[j]<a[i])&&(j<=t))j++;
		ans=ans+(j-mid-1);
	}
	i=s;j=mid+1;
	while(i<=mid&&j<=t){
		if(a[i]<a[j])
		d[k++]=a[i++];
		else d[k++]=a[j++];
	}
	while(i<=mid)
	d[k++]=a[j++];
	while(j<=t)
	d[k++]=a[j++];
	for(int r=s;r<=t;r++){
		a[r]=d[r];
	}
	return;
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++)cin>>a[i];
	merge(1,n);
	cout<<ans;
	return 0;
 }