void swap_index(int i, int j)
	{
		do {byte _=sign[i]; sign[i]=sign[j]; sign[j]=_;} while(false);
		do {int _=index[i]; index[i]=index[j]; index[j]=_;} while(false);
		do {double _=QD[i]; QD[i]=QD[j]; QD[j]=_;} while(false);
	}