#include<iostream>
#include<cstring>
#include<algorithm>

using namespace std;

const int N = 1e5+10;

typedef long long LL;

int n;
int q[N],w[N];
LL ans;

void merge_sort(int l, int r)
{
    if(l >= r)  return;

    int mid=l+r>>1;

    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]) w[k++] = q[i++];
        else
        {
            w[k++] = q[j++];
            ans += mid-i+1;
        }
    while(i <= mid) w[k++] = q[i++];
    while(j <= r)   w[k++] = q[j++]; 

    for(i=l,j=0;i<=r;i++,j++)   q[i] = w[j];
}
int main()
{
    scanf("%d", &n);
    for(int i=0;i<n;i++)    scanf("%d",&q[i]);

    merge_sort(0,n-1);

    cout<<ans<<endl;
    return 0;
}