#include<bits/stdc++.h>

using namespace std;

const int N=1e6;

typedef long long ll;

int a[N],b[N],n;

ll total=0;

inline int read()

{

char c=getchar();int num=0;

for(;!isdigit(c);c=getchar());

for(;isdigit(c);c=getchar())

    num=num*10+c-'0';
    
return num;

}

void mergesort(int l,int r){

if(l==r)

	return;

int mid=(l+r)/2;

mergesort(l,mid);	

mergesort(mid+1,r);

int x=l,y=mid+1,z=l;

while(x<=mid&&y<=r){

	if(a[x]>a[y]){

		b[z++]=a[y++];	
  
		total=total+mid-x+1;
  
	}

	else

		b[z++]=a[x++];
  
}

while(x<=mid)

	b[z++]=a[x++];

while(y<=r)

	b[z++]=a[y++];

for(int i=l;i<=r;i++)

	a[i]=b[i];

}

int main() {

cin>>n;

for(int i=1;i<=n;i++)

	a[i]=read();

mergesort(1,n);

cout<<total<<endl;

return 0;

}