#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
#include<vector>
#include<cstdlib>
#include<locale>
#include<stack>
#include<bits/stdc++.h>
using namespace std;
int a[1000001],b[10000001],n,cnt=0;
void merge(int left,int right) {
	int i,j,k,mid=(left+right)/2;
	if(left==right) return ;
	merge(left,mid);
	merge(mid+1,right);
	i=left;
	j=mid+1;
	k=left;
	while(i<=mid && j<=right) {
		if(a[i]>a[j]) {
			b[k++]=a[j++];
		} else {
			b[k++]=a[i++];
			cnt+=mid-i+1;
		}
	}
	while(i<=mid) {
		b[k++]=a[i++];
	}
	while(j<=right) {
		b[k++]=a[j++];
	}
	for(int i=left;i<=right;i++)
	{
		a[i]=b[i];
	}
}
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	merge(1,n);
	cout<<cnt;
	return 0;
}