[Usaco2006 Open]County Fair Events 参加节日庆祝

时间限制:5s      空间限制:64MB

题目描述

Farmer John has returned to the County Fair so he can attend the special events (concerts, rodeos, cooking shows, etc.). He wants to attend as many of the N (1 <= N <= 10,000) special events as he possibly can. He's rented a bicycle so he can speed from one event to the next in absolutely no time at all (0 time units to go from one event to the next!). Given a list of the events that FJ might wish to attend, with their start times (1 <= T <= 100,000) and their durations (1 <= L <= 100,000), determine the maximum number of events that FJ can attend. FJ never leaves an event early.

 

有N个节日每个节日有个开始时间,及持续时间. 牛想尽可能多的参加节日,问最多可以参加多少. 注意牛的转移速度是极快的,不花时间.


输入格式

* Line 1: A single integer, N.

* Lines 2..N+1: Each line contains two space-separated integers, T and L, that describe an event that FJ might attend.


输出格式

* Line 1: A single integer that is the maximum number of events FJ can attend.


样例输入

7               
1 6
8 6
14 5
19 2
1 8
18 3
10 6

INPUT DETAILS:

Graphic picture of the schedule:
         11111111112
12345678901234567890---------这个是时间轴.
--------------------
111111 2222223333344
55555555 777777  666

这个图中1代表第一个节日从1开始,持续6个时间,直到6.


样例输出

4

OUTPUT DETAILS:

FJ can do no better than to attend events 1, 2, 3, and 4.

提示

没有写明提示


题目来源

Silver