#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=100010;

int n;
int q[N],tmp[N];

ll merge_sort(int l,int r)
{
    if(l>=r) return 0;
    int mid= l + r >>1;
    ll res =merge_sort(l,mid)+merge_sort(mid+1,r);

    //归并的过程，前面一个二分
    int k=0,i=l,j=mid+1;//分别为第一段的开头和第二段的开头
    while(i<=mid&&j<=r)
    if(q[i]<=q[j]) tmp[k++] =q[i++];
    else
    {
        tmp[k++]=q[j++];
        res += mid-i+1;//Sj等于mid-i+1个数,每次要输出q[j]时加mid-i+1
    }
    while (i<=mid) tmp[k++]=q[i++];//如果剩余左半边则全部加进去
    while (j<=r) tmp[k++]=q[j++];//如果剩余右半边则全部加进去

    //最后copy进去
    for(int i=l,j=0;i<=r;i++,j++) q[i]=tmp[j];

    return res;
}

int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cin>>q[i];
    }
    cout<<merge_sort(0,n-1)<<endl;
    return 0;
}