#include <bits/stdc++.h>
using namespace std;
int s1[2000],s2[2000];
long long ans;
void merge(int l,int mid,int r)
{
	if (l==r) return;
	merge(l,(l+mid)/2,mid);
	merge(mid+1,(mid+1+r)/2,r);
	int i=l,j=mid+1,k=l;
	while(i<=mid && j<=r)
	{
		if (s1[i]<=s1[j]) s2[k++]=s1[i++];//从大到小">",从小到大"<" 
		else
		{
			s2[k++]=s1[j++];
			ans+=mid-i+1;
		}
	}
	while(i<=mid) s2[k++]=s1[i++];
	while(j<=r) s2[k++]=s1[j++];
	for(i=l;i<=r;i++) s1[i]=s2[i];
}
/*
void MergeSort(int L,int R)
{
	int Mid;
	if(L<R)
	{
		Mid=(L+R)/2;
		MergeSort(L,Mid);
		MergeSort(Mid+1,R);
		merge(L,Mid,R);
	}
}
*/
int main()
{
	//逆序对
	int n,i;
	scanf("%d",&n);
	for(i=1;i<=n;i++) scanf("%d",&s1[i]);
	merge(1,(1+n)/2,n);
	printf("%lld",ans);
}