题目链接：https://vjudge.net/contest/358908#problem/H

题目大意：给你一个序列，问你这个序列经过冒泡排序形成的非递减序列所需要的次数

　　很经典的线段树求逆序数的题，对于序列中的一个数字来说，把他移动到在非递减序列中的位置的交换次数就是他前面

比他大的数字的数目，至于每次交换的后续性这是不用考虑的，因为这里只是说相对位置

#include<set>
#include<map>
#include<stack>
#include<queue>
#include<cmath>
#include<cstdio>
#include<cctype>
#include<string>
#include<vector>
#include<climits>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define endl '\n'
#define rtl rt<<1
#define rtr rt<<1|1
#define lson rt<<1, l, mid
#define rson rt<<1|1, mid+1, r
#define maxx(a, b) (a > b ? a : b)
#define minn(a, b) (a < b ? a : b)
#define zero(a) memset(a, 0, sizeof(a))
#define INF(a) memset(a, 0x3f, sizeof(a))
#define IOS ios::sync_with_stdio(false)
#define _test printf("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n")
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, ll> P2;
const double pi = acos(-1.0);
const double eps = 1e-7;
const ll MOD =  1000000007LL;
const int INF = 0x3f3f3f3f;
const int _NAN = -0x3f3f3f3f;
const double EULC = 0.5772156649015328;
const int NIL = -1;
template<typename T> void read(T &x){
    x = 0;char ch = getchar();ll f = 1;
    while(!isdigit(ch)){if(ch == '-')f*=-1;ch=getchar();}
    while(isdigit(ch)){x = x*10+ch-48;ch=getchar();}x*=f;
}
const int maxn = 1e6+10;
int arr[maxn], t[maxn], tree[maxn<<2];
void build(int rt, int l, int r) {
    tree[rt] = 0;
    if (l==r) return;
    int mid = (l+r)>>1;
    build(lson);
    build(rson);
}
void change(int pos, int rt, int l, int r) {
    if (l==r) {
        tree[rt] |= 1;
        return;
    }
    int mid = (l+r)>>1;
    pos <= mid ? change(pos, lson) : change(pos, rson);
    tree[rt] = tree[rtl] + tree[rtr];
}
ll find(int st, int ed, int rt, int l, int r) {
    if (st<=l && ed>=r) 
        return  tree[rt];
    int mid = (l+r)>>1; ll ans = 0;
    if (st<=mid)
        ans += find(st, ed, lson);
    if (ed>mid)
        ans += find(st, ed, rson);
    return ans;
}
int main(void) {
    int n;
    while(~scanf("%d", &n) && n) {
        for (int i = 1; i<=n; ++i) {
            scanf("%d", &arr[i]);
            t[i] = arr[i];
        }
        sort(t+1, t+n+1);
        int last = unique(t+1, t+n+1)-t;
        for (int i = 1; i<=n; ++i)
            arr[i] = lower_bound(t+1, t+last, arr[i])-t;
        ll sum = 0;
        for (int i = 1; i<=n; ++i) {
            sum += find(arr[i], last, 1, 1, last);
            change(arr[i], 1, 1, last);
        }
        printf("%lld\n", sum);
        build(1, 1, last);
    }
    return 0;
}