#include <bits/stdc++.h>
using namespace std;
long long n, sum, a[100001];
int main()
{
    cin >> n;
    for (int i = 1; i < n; ++ i)
        cin >> a[i];
    for (int i = 1; i < n; ++i)
        for (int j = j; j <= n - i; ++j)
            if (a[j] > a[j + 1])
            {
                swap(a[j], a[j + 1]);
                sum ++;
            }
    cout << sum;
    return 0;
}