#include<bits/stdc++.h>
using namespace std;
int a[500005],c[500005],n;
long long ans=0;
void m(int l,int r)
{
    if(l==r)    return ;
    int mid=(l+r)/2;
    int i=l,j=mid+1,k=r;
    m(l,mid);
	m(mid+1,r); 
    while(i<=mid&&j<=r)
        if(a[i]<=a[j])    c[k++]=a[i++];
        else    c[k++]=a[j++],ans+=mid-i+1;
    while(i<=mid)   c[k++]=a[i++];
    while(j<=l)     c[k++]=a[j++];
    for(int x=l;x<=r;x++)   a[x]=c[x];
}
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)   scanf("%d",&a[i]);
    m(1,n);
    printf("%lld",ans);
    return 0;
}