#include<iostream>
using namespace std;

const int N =100010;
int q[N],tmp[N];
typedef long long LL;

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);

    int i=l,j = mid+1,k=0;

    while(i<=mid && j<=r)
    {
        if(q[i]<=q[j]) tmp[k++] = q[i++];
        else
        {
            tmp[k++] = q[j++];
            res += mid - i + 1;
        }
    }

    //扫尾
    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;
    scanf("%d",&n);
    for(int i=0;i<n;i++) scanf("%d",q+i);

    cout << merge_sort(0,n-1);


    return 0;
}