Segments

TimeLimit:1000MS  MemoryLimit:256MB
64-bit integer IO format:%I64d
未提交 | 登录后收藏
Problem Description

You are given n segments on the Ox-axis. You can drive a nail in any integer point on the Ox-axis line nail so, that all segments containing this point, are considered nailed down. If the nail passes through endpoint of some segment, this segment is considered to be nailed too. What is the smallest number of nails needed to nail all the segments down?

Input

The first line of the input contains single integer number n (1 ≤ n ≤ 1000) — amount of segments. Following n lines contain descriptions of the segments. Each description is a pair of integer numbers — endpoints coordinates. All the coordinates don't exceed 10000 by absolute value. Segments can degenarate to points.

Output

The first line should contain one integer number — the smallest number of nails needed to nail all the segments down. The second line should contain coordinates of driven nails separated by space in any order. If the answer is not unique, output any.

SampleInput 1
2
0 2
2 5
SampleOutput 1
1
2
SampleInput 2
5
0 3
4 2
4 8
8 10
7 7
SampleOutput 2
3
7 10 3
Submit
题目统计信息详细
总AC数10
通过人数8
尝试人数9
总提交量14
AC率57.14%
AC该题后可以添加标签
贴完标签可以获得20ACB。
并且可以获得本题所有提交代码查看权限。
点击标题可以显示标签。
如果你还没认真思考过这题,请不要查看标签
如果您已经通过了该题,请务为该题贴上标签

T^T Online Judge

[BUG反馈] [FAQ] [闽ICP备17026590号-1]
当前版本:3.24 系统时间: