问题描述：

某石油公司计划建造一条由东向西的主输油管道。该管道要穿过一个有n 口油井的油田。从每口油井都要有一条输油管道沿最短路经(或南或北)与主管道相连。如果给定n口油井的位置,即它们的x 坐标（东西向）和y 坐标（南北向）,应如何确定主管道的最优位置,即使各油井到主管道之间的输油管道长度总和最小的位置?

编程任务：

给定n 口油井的位置,编程计算各油井到主管道之间的输油管道最小长度总和。

-Problem Descr iption: A plan to build a oil from east to west of the main pipeline. The pipeline to pass through a field of n wells. Wells from each must have a pipeline along the shortest path (or South or North) connected with the director of Road. If given the location of oil wells n, that is, their x coordinates (east-west) and y coordinates (north-south), head of Road should be how to determine the optimal position, even if the well-to-head Road, the pipeline length between the sum of the smallest location? programming tasks: to set the location of oil wells n, programming the calculation of the well-to-head Road, the pipeline between the sum of the minimum length.