# [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