#include<bits/stdc++.h>
using namespace std;
const int N=10100100;
int n,a[N],b[N],ans=0;

void Merge(int L,int mid,int R){
	int i=L,j=mid+1,k=0;
	while(i<=mid&&j<=R){
		if(a[i]<=a[j]){
			b[k++]=a[i++];
		}else{
			b[k++]=a[j++],ans+=mid-i+1;
		}
	}
	while(i<=mid)b[k++]=a[i++];
	while(j<=R)b[k++]=a[j++];
	for(int i=L,k=0;i<=R;i++){
		a[i]=b[k++];
	}
}
void mergesort(int L,int R){
	if(L<R){
		int mid=(L+R)/2;
		mergesort(L,mid);
		mergesort(mid+1,R);
		Merge(L,mid,R);
	}
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>a[i];
	mergesort(1,n);
		cout<<ans;
	return 0;
} 

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