#include<iostream>
using namespace std;
const int N=1e5+10;
int temp[N];
long long f;
long long merge(int *a ,int l,int r)
{
    if(l>=r) return 0;
    int mid=l+r>>1,l1=l,r1=mid+1,index=0;
    merge(a,l,mid),merge(a,mid+1,r);
    while(l1<=mid && r1<=r)
        if(a[l1]>a[r1]) temp[index++]=a[r1++],f+=mid-l1+1;
        else temp[index++]=a[l1++];
    while(l1<=mid) temp[index++]=a[l1++];
    while(r1<=r) temp[index++]=a[r1++];
    for(int i=l,j=0;i<=r;j++,i++) a[i]=temp[j];
    return f;
}
int main()
{
    int n;
    cin>>n;
    int a[N];
    for(int i=0;i<n;i++) cin>>a[i];
    cout<<merge(a,0,n-1);
    return 0;
}