#include <bits/stdc++.h>
#define syosu(x) fixed<<setprecision(x)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef pair<double,double> pdd;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vp> vvp;
typedef vector<pll> vpll;
typedef pair<int,P> pip;
typedef vector<pip> vip;
const int inf=1<<30;
const ll INF=1ll<<60;
const double pi=acos(-1);
const double eps=1e-9;
const ll mod=1e9+7;
const int dx[4]={0,1,0,-1},dy[4]={1,0,-1,0};

class Segment_Tree{
	private:
	int n;
	vi date;
	int Rec(int a,int b,int k,int l,int r){
		if(r<=a||b<=l) return 0;
		if(a<=l&&r<=b) return date[k];
		int m=(l+r)/2;
		return Rec(a,b,k*2+1,l,m)+Rec(a,b,k*2+2,m,r);
	}
	public:
	Segment_Tree(int n_){
		n=1;
		while(n<n_) n*=2;
		date=vi(2*n-1);
	}
	void Update(int k,int x){
		k+=n-1;
		date[k]+=x;
		while(k>0){
			k=(k-1)/2;
			date[k]=date[k*2+1]+date[k*2+2];
		}
	}
	int Query(int a,int b){
		return Rec(a,b,0,0,n);
	}
	int Open(int k){return date[k+n-1];}
};

int n;

int main(){
	cin>>n;
	Segment_Tree st(n);
	ll t=0;
	for(int i=0;i<n;i++){
		int A;
		cin>>A;
		st.Update(A-1,1);
		t+=st.Query(A,n);
	}
	cout<<t<<endl;
}