#include<bits/stdc++.h>
using namespace std;
int n,a[500005],b[500005];
long long s=0;
void f(int l,int r){
	if(r<=l) return;
	int mid=(l+r)/2;
	f(l,mid);f(mid+1,r);
	int h1=l,h2=mid+1,h=l;
	while(h1<=mid&&h2<=r){
if(a[h1]<=a[h2])
b[h++]=a[h1++];
		else b[h++]=a[h2++],s+=mid-h1+1; 
	}
	while(h1<=mid) b[h++]=a[h1++];
	while(h2<=r) b[h++]=a[h2++];
	for(int i=1;i<=r;i++) 		a[i]=b[i];
	}
int main(){
scanf("%d",&n);
for(int i=1;i<=n;i++){
	scanf("%d",&a[i]);
}
f(1,n);
printf("%lld",s);
return 0;
}```