#include <iostream>
#define MAX 100005
#define ll long long
using namespace std;

int a[MAX], n;
ll c[MAX];

ll getBit(int x)
{
    ll tong=0;
    for (;x>0; x&=(x-1))
        tong+=c[x];
    return tong;
}

ll update(int x)
{
    for (;x<=MAX; x+=x&(-x))
    {
        c[x]+=1;
    }
}

void Solve()
{
    ll kq=0;
    for (int i=n; i>=1; i--)
    {
        kq+=getBit(a[i]);
        update(a[i]+1);
    }
    cout<<kq;
}

int main()
{
    cin >> n;
    for (int i=1; i<=n; i++) cin >> a[i];
    Solve();
    return 0;
}