#include<iostream>
using namespace std;
const int N=5e6+10;
struct node{
	int sum,lson,rson;
}tree[4*N];
int cnt,root;
inline void upd(int &pos,int dot,int c,int l,int r){
	if(pos==0) pos=++cnt;
	if(l<=dot&&dot<=r) tree[pos].sum+=c;
	if(dot<l||r<dot||l==r) return;
	int mid=(l+r)/2;
	upd(tree[pos].lson,dot,c,l,mid);
	upd(tree[pos].rson,dot,c,mid+1,r);
}
inline int ask(int &pos,int lft,int rgt,int l,int r){
	if(lft<=l&&r<=rgt) return tree[pos].sum;
	if(pos==0||rgt<l||r<lft) return 0;
	int mid=(l+r)/2;
	return ask(tree[pos].lson,lft,rgt,l,mid)+ask(tree[pos].rson,lft,rgt,mid+1,r);
}
int a[N];
int n;
long long ans;
int main(){
	ios::sync_with_stdio(false);
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		ans+=ask(root,a[i]+1,1e9,1,1e9);
		upd(root,a[i],1,1,1e9);
	}
	cout<<ans;
	return 0;
}