线段覆盖问题已知一维空间N条线段。每条线段按照端点Ai和Bi（Ai<Bi, i=1,2...N）定义。端点坐标为整数。有些线段可能相交。编程实现删除最少数目的线段，使得余下的任意两条线段不相交。并输出剩余的线段数和具体线段。-Line coverage of the known one-dimensional space N be line segments. In accordance with the endpoint of each segment Ai and Bi (Ai <Bi, i = 1,2 ... N) defined. Integer endpoint coordinates. Some segments may intersect. Programming to delete at least the number of line segments, making the remaining two segments of arbitrary disjoint. And output the remaining segment number and the specific segment.