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径(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)，应该如何确定主管道的最优位置，即使个油井到主管道之间的输油管道长度总和最小的位置？

(2) 算法设计

给定n口油井的位置，计算个油井到主管道之间的输油管道最小长度总和。

(3) 数据输入

由文件提供数据。文件的第一行为油井数n，1<=n<=10000；接下来n行是油井的位置，每行2个整数x和y，-10000<=x,y<=10000。-An oil company plans to construct a east to west from the main pipeline. The pipeline to pass through an oil field n wells. Wells from each must have a pipeline along the shortest path (or South or North) Road, connected with the director. If given the location of oil wells in n, that is, their x coordinates (east-west) and y coordinates (north-south), director Road should be how to determine the optimal location, even if the wells to the Road, director of the oil pipeline between the length of the sum of the smallest location?

(2) Algorithm Design

N given the location of oil wells, oil wells to calculate Road director of the oil pipeline between the sum of minimum length.

(3) data entry

Provide data from the document. Documents the first acts of a few oil wells n, 1 <= n <= 10000　next n lines are the location of wells, each row two integers x and y,-10000 <= x, y <= 10000.