#include <iostream>
#include <vector>
#define int long long 
using namespace std;
int ans=0;
void mergesort(vector<int>&a,int l,int mid,int r){
	int *tmp=new int[r-l+1];
	int i=l,j=mid+1,index=0;
	while(i<=mid&&j<=r){
		if(a[i]<=a[j])tmp[index++]=a[i++];
		else{
			tmp[index++]=a[j++];
			ans+=mid-i+1;
		}
	}
	while(i<=mid)tmp[index++]=a[i++];
	while(j<=r)tmp[index++]=a[j++];
	for(int i=0;i<index;i++){
		a[l+i]=tmp[i];
	}
	delete[]tmp;
}
void merge_up2down(vector<int>&a,int l,int r){
	if(l>=r)return;
	int mid=(l+r)>>1;
	merge_up2down(a,l,mid);
	merge_up2down(a,mid+1,r);
	mergesort(a,l,mid,r);
}
signed main(){
	int n;
	cin>>n;
	vector<int> a(n);
	for(int i=0;i<n;i++)cin>>a[i];
	merge_up2down(a,0,n-1);
	cout<<ans<<endl;
	return 0;
}