Given $n$ line segments on the number line. Choose the maximum number of line segments such that no two line segments share a common point.
### Input
- The first line contains two integers $n$.
- The next $n$ lines each contain two integers $l, r$, representing a line segment extending from point $l$ to $r$ on the number line.
### Output
- Print an integer, the maximum number of line segments that can be chosen.
### Constraints
- $1 \le n \le 10^5$.
- $1 \le l \le r \le 10^9$.
### Example
Input:
```
5
6 8
2 3
5 6
2 5
2 5
```
Output:
```
2
```
