#include<iostream>
using namespace std;

int n,q[100000],temp[100000];
long long ans;
long long merge_sort(int q[],int l,int r){
    if(l>=r)return 0;
    int i=l,mid=l+r>>1,j=mid+1,k=0;
    merge_sort(q,l,mid),merge_sort(q,mid+1,r);

    while(i<=mid&&j<=r){
        if(q[i]<=q[j])temp[k++]=q[i++];
        else {
            temp[k++]=q[j++];
            ans+=mid-i+1;
        }
    }
    while(i<=mid)temp[k++]=q[i++];
    while(j<=r)temp[k++]=q[j++];
    for(i=l,j=0;i<=r;)q[i++]=temp[j++];
}


int main(){
    cin>>n;
    for(int i=0;i<n;i++)scanf("%d",q+i);
    merge_sort(q,0,n-1);
    cout<<ans;
    return 0;
}