2299

/*
树状数组，归并排序
*/

// include file
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>
#include <ctime>

#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <bitset>

#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <list>
#include <functional>

using namespace std;

// typedef
typedef long long LL;
typedef unsigned long long ULL;

// 
#define read freopen("in.txt","r",stdin)
#define write freopen("out.txt","w",stdout)
#define FORi(a,b,c) for(int i=(a);i<(b);i+=c)
#define FORj(a,b,c) for(int j=(a);j<(b);j+=c)
#define FORk(a,b,c) for(int k=(a);k<(b);k+=c)
#define FORp(a,b,c) for(int p=(a);p<(b);p+=c)
#define FORii(a,b,c) for(int ii=(a);ii<(b);ii+=c)
#define FORjj(a,b,c) for(int jj=(a);jj<(b);jj+=c)
#define FORkk(a,b,c) for(int kk=(a);kk<(b);kk+=c)

#define FF(i,a)    for(int i=0;i<(a);i++)
#define FFD(i,a)   for(int i=(a)-1;i>=0;i--)

#define Z(a) (a<<1)
#define Y(a) (a>>1)

const double eps = 1e-6;
const double INFf = 1e100;
const int INFi = 1000000000;
const LL INFll = (LL)1<<62;
const double Pi = acos(-1.0);

template<class T> inline T sqr(T a){return a*a;}
template<class T> inline T TMAX(T x,T y)
{
	if(x>y) return x;
	return y;
}
template<class T> inline T TMIN(T x,T y)
{
	if(x<y) return x;
	return y;
}
template<class T> inline void SWAP(T &x,T &y)
{
	T t = x;
	x = y;
	y = t;
}
template<class T> inline T MMAX(T x,T y,T z)
{
	return TMAX(TMAX(x,y),z);
}
template<class T> inline T MMIN(T x,T y,T z)
{
	return TMIN(TMIN(x,y),z);
}


// code begin
// 最多50万个，离散化先
int N;
struct node
{
	int v;
	int dx;
	friend bool operator<(node a,node b)
	{
		return a.v<b.v;
	}
};
node D[500010];
int Ndx[500010],Nx;
LL Bit[500010];
// 是对数值进行索引
inline int lowBit(int x)
{
	return x&(-x);
}

void update(int x,int c)
{
	for(int i=x;i>0;i-=lowBit(i))
	{
		Bit[i]+=c;
	}
}
LL getSum(int x)
{
	LL ans = 0;
	for(int i=x;i<Nx;i+=lowBit(i))
	{
		ans += Bit[i];
	}
	return ans;
}
int main()
{
	read;
	write;
	while(scanf("%d",&N)==1)
	{
		if(N==0) break;
		FORi(0,N,1)
		{
			scanf("%d",&D[i].v);
			D[i].dx = i;
		}
		sort(D,D+N);
		Nx = 1; // 其实就是离散化后的数值
		Ndx[D[0].dx] = Nx++;	
		FORi(1,N,1)
		{
			if(D[i].v==D[i-1].v)
				Ndx[D[i].dx] = Nx;
			else
				Ndx[D[i].dx] = Nx++;
			//保证离散后，原来相等还是相等
		}
		//离散化后
		LL ans = 0;
		memset(Bit,0,sizeof(Bit));
		FORi(0,N,1)
		{
			// Ndx[i]，离散后的编号在第i的数值
			ans += getSum(Ndx[i]);
			update(Ndx[i],1);
		}
		printf("%lld\n",ans);
	}
	return 0;
}