> #include<iostream>
> using namespace std;
> long long a[500000],c[500000];
> long long MergeSort(long long a[],long long c[],int left,int right)
> {
> 	int i,j,mid,temp,count;
> 	long long   total=0;
> 	if(left>right)
> 	return 0;
> 		mid=(left+right)/2;
> 		count=0;
> 		i=left;
> 		j=mid+1;
> 		while(i<=mid && j<=right)
> 		{
> 			if (a[i]>a[j]) 
>             {
> 				total+=mid-i+1;//从右表移出一个元素，同时 total 累加左表此时的元素个数 
> 				c[count++]=a[j++];
> 			} 
> 			else 
>             {
> 				c[count++]=a[i++];
> 			}
> 	   }
> 	return total;
> }
> int main()
> {
> 	int n,i,j;
> 	long long  total;
> 	while (1)
> 	{   scanf("%d",&n);
> 	   if(n==0)
> 	   break;
> 		for (i=0;i<n;i++)
> 		{
>         scanf("%lld",&a[i]);
>         }
> 		total=MergeSort(a,c,0,n-1);
> 		printf("%lld\n",total);
> 	}
>        system("pause"); 
>        return 0;
> }
>