#include<iostream>
#include<cstdio>
using namespace std;
typedef long long LL;
const int N=1e5+10;
int q[N],tmp[N];          //temporary暂时的
LL merge_sort(int q[],int l,int r){
    if(l>=r) return 0;
    int mid=l+r>>1;
    LL res =merge_sort(q,l,mid)+merge_sort(q,mid+1,r);        //递归  把所有的无限递归为两数组比较
    int k=0,i=l,j=mid+1;
    while(i<=mid&&j<=r){
        if(q[i]<=q[j]) tmp[k++]=q[i++];
        else {

            res+=mid-i+1;
             tmp[k++]=q[j++];
        }
    }
    while(i<=mid) tmp[k++]=q[i++];
    while(j<=r)   tmp[k++]=q[j++];
    for(int i=l,j=0;i<=r;i++,j++) q[i]=tmp[j];
    return res;
}
int main(){
    int n;
    cin>>n;
    for(int i=0;i<n;i++) scanf("%d",&q[i]);
    cout<< merge_sort(q,0,n-1)<<endl;
    return 0;

}