#include <cstdio>
#include <cstdlib>
#include <iostream>
using namespace std;
const int MAX=501000;
int n,t[MAX],a[MAX];
long long sum;
void merge(int l,int mid,int r)
{
	int p=0;
	int i=l,j=mid+1;
	while(i<=mid&&j<=r)
	{
		if(a[i]>a[j])
		{
			t[p++]=a[j++];
			sum=sum+mid-i+1;
		}
		else t[p++]=a[i++];
	}
	while(i<=mid) t[p++]=a[i++];
	while(j<=r)  t[p++]=a[j++];
	for(i=0;i<p;i++) a[l+i]=t[i];
}

void mergesort(int l,int r)
{
	if(l<r)
	{
		int mid=(r-l)/2+l;
		mergesort(l,mid);
		mergesort(mid+1,r);
		merge(l,mid,r);
	}
}
 
int main()
{
	freopen("sop.in","r",stdin);
	freopen("sop.out","w",stdout);
 	scanf("%d\n",&n);
	sum=0;
	for(int i=0;i<n;i++) scanf("%d",&a[i]);
	mergesort(0,n-1);
	printf("%lld\n",sum);
	return 0;
}