#include<algorithm>
#include<stdio.h>
#include<ctype.h>
#define int long long
namespace io{
	int Read(){
		char c=getchar();
		int x=0,d=1;
		while(!isdigit(c)){
			if(c=='-')d=-1;
			c=getchar();
		}
		while(isdigit(c))
			x=x*10-48+c,c=getchar();
		return x*d;
	}
	void pr(int x){
		if(!x)return;
		pr(x/10);
		putchar(x%10+48);
	}
	void Print(int x){
		if(x){
			if(x<0)x=-x,putchar('-');
			pr(x);
		}
		else putchar('0');
		putchar('\n');
	}
}
using namespace io;
using std::sort;
const int N=555555;
struct node{
	int id,val;
	inline bool operator<(const node &x)const{return val<x.val;}
}a[N];
int n;
class Fenwick_Tree{
private:
	int t[N];
	#define lowbit(x) x&-x
	#define ub(x) x+=lowbit(x)
	#define db(x) x-=lowbit(x)
public:
	void Change(int x){
		while(x<=n)t[x]++,ub(x);
	}
	int Query(int x){
		int s=0;
		while(x)s+=t[x],db(x);
		return s;
	}
};
Fenwick_Tree QwQ;
signed main(){
	int s=0;
	n=Read();
	for(int i=1;i<=n;i++)a[i]=(node){Read(),i};
	sort(a+1,a+n+1);
	for(int i=n;i>0;i--)QwQ.Change(a[i].id),s+=QwQ.Query(a[i].id-1);
	Print(s);
	return 0;
}

RT，求调QwQ