#include<bits/stdc++.h>
using namespace std;
int n,ans;
int a[500001],c[500001];
void merge_sort(int l,int r)
{
	if(l>=r)return;
	int m=(l+r)/2;
	merge_sort(l,m);
	merge_sort(m+1,r);
	int h=l,h2=m+1;
	for(int i=l;i<=r;i++)
	{
		if(h>m)
		{
			c[h+h2-m]=a[h2++];
		}
		else if(h2>r)
		{
			c[h+h2-m]=a[h++];
		}
		else if(a[h]>a[h2])
		{
			ans+=r-h2+1;
			c[h+h2-m]=a[h++];
		}
		else
		{
			c[h+h2-m]=a[h2++];
		}
	}
}
int read()
{
	int s=0,t=1;
	char c=getchar();
	while(c<'0'||c>'9')
	{
		if(c=='-')t=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9')
	{
		s=s*10+c-'0';
		c=getchar();
	}
	return s*t;
}
void out(int s)
{
	if(s==0)return;
	if(s<0)
	{
		putchar('-');
		out(-s);
		return;
	}
	out(s/10);
	putchar(s%10+'0');
}
int main()
{
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	n=read();
	for(int i=1;i<=n;i++)
	{
		a[i]=read();
	}
	merge_sort(1,n);
	out(ans);
	return 0;
}