Description

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.

Format

Input

• 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.

Output

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

Samples

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

4

Limitation

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.

OUTPUT DETAILS:

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