PROGRAMMING:Message Sending
The 18th China Jiliang University Programming Contest is approaching, Little Gyro wants to send plenty of messages by e-mail to invite people participating in the competition. However, Little Gyro only has one e-mail account ( acm309@126.com ) to send these messages. In order to invite more candidates as possible, Little Gyro needs your help.
Given the whole time table of the e-mail messages Little Gyro wants to send, including the start time and the end time of each message, and it usually doesn't take the same time when Little Gyro sending different e-mail messages. Besides, Little Gyro cannot send two or more messages at the same time. That means Little Gyro can send the next message only if the start time after the end time of the previous one.
Now Little Gyro wants to know how many e-mail messages he can send to the competition candidates at most.
### Input Specification:
Each input file only contains one test case.
The first line contains an integer $$n$$ (1 ≤ $$n$$ ≤ $$10^5$$), indicating the amount of the message time table.
In the following $$n$$ lines, each line contains two integers $$s_ i$$, $$e_ i$$ (0 ≤ $$s_ i$$, $$e_ i$$ ≤ $$10^9$$), indicating the start time and the end time of the $$i$$-th message.
### Output Specification:
For each test case output an integer indicating the amount of e-mail messages Little Gyro can sent at most.
### Sample Input:
```in
five
6 8
1 5
0 2
2 3
0 1
```
### Sample Output:
```out
three
```
answer：If there is no answer, please comment
Given the whole time table of the e-mail messages Little Gyro wants to send, including the start time and the end time of each message, and it usually doesn't take the same time when Little Gyro sending different e-mail messages. Besides, Little Gyro cannot send two or more messages at the same time. That means Little Gyro can send the next message only if the start time after the end time of the previous one.
Now Little Gyro wants to know how many e-mail messages he can send to the competition candidates at most.
### Input Specification:
Each input file only contains one test case.
The first line contains an integer $$n$$ (1 ≤ $$n$$ ≤ $$10^5$$), indicating the amount of the message time table.
In the following $$n$$ lines, each line contains two integers $$s_ i$$, $$e_ i$$ (0 ≤ $$s_ i$$, $$e_ i$$ ≤ $$10^9$$), indicating the start time and the end time of the $$i$$-th message.
### Output Specification:
For each test case output an integer indicating the amount of e-mail messages Little Gyro can sent at most.
### Sample Input:
```in
five
6 8
1 5
0 2
2 3
0 1
```
### Sample Output:
```out
three
```
answer：If there is no answer, please comment