e-olymp

Segments

Some segments are given on a line. What is the maximum number of segments can be selected so that no two of them intersects? The segments are considered open.

Input

The first line contains the number of segments n (1n105). Next n lines describe the segments: i-th line contains two integers li and ri (1li < ri109) - the coordinates of segment's starting and ending point.

Output

Print the maximum number of non intersecting segments.

Time limit 1 second
Memory limit 128 MiB
Input example #1
2
1 2
3 5
Output example #1
2
Input example #2
2
1 3
2 6
Output example #2
1
Input example #3
3
2 4
3 5
1 3
Output example #3
2
Author Ivan Kazmenko