归并排序
const int maxn = 555555;
int n, a[maxn], b[maxn];
typedef long long ll;
ll mergesort(int l, int r) {
    if (l == r) return 0;
    ll cnt = 0;
    int m = (l + r) >> 1;
    cnt = mergesort(l, m) + mergesort(m + 1, r);
    int i = l, j = m + 1, k = l;
    while(i <= m && j <= r) {
        if (a[i] <= a[j]) b[k++] = a[i++];
        else {
            b[k++] = a[j++];
            cnt += (m - i + 1);
        }
    }
    while(i <= m) b[k++] = a[i++];
    while(j <= r) b[k++] = a[j++];
    for (i = l; i <= r; i++) a[i] = b[i];
    return cnt;
}
int main () {
    while(~scanf("%d", &n) && n) {
        for (int i = 0; i < n; i++) scanf("%d", a + i);
        printf("%I64d\n", mergesort(0, n - 1));
    }
    return 0;
}

//树状数组
const int maxn = 555555;
typedef long long ll;
int n;
ll a[maxn], pos[maxn];
struct node {
    int v, i;
}e[maxn];
bool cmp(node s, node v){
    return s.v < v.v;
}
inline int lowbit(int x) {
    return (x & -x);
}
void update(int x, int v) {
    for (int i = x; i <= n; i += lowbit(i)) a[i] += v;
}
ll query(int x) {
    ll ret = 0;
    for (int i = x; i; i -= lowbit(i)) ret += a[i];
    return ret;
}
int main () {
    while(scanf("%d", &n) && n) {
        for (int i = 1; i <= n; i++) {
            a[i] = 0;
            scanf("%d", &e[i].v);
            e[i].i = i;
        }
        //离散化
        sort(e + 1, e + n + 1, cmp);
        for (int i = 1; i <= n; i++) pos[i] = e[i].i;
        int x;
        ll ret = 0;
        for (int i = 1; i <= n; i++) {
            ret += query(pos[i]);
            update(pos[i], 1);
        }
        printf("%I64d\n", (ll)n * (n - 1) / 2 - ret);
    }
    return 0;
}