Covering segments by points
Given n segments, find the minimal possible number of points such that each segment contains at least one point.
The first line contains the number 1≤n≤100 of segments. Each of the following n lines contains two integers 0≤l≤r≤109 defining the endpoints of a segment. Output the optimal number m of points and then m points.
Sample Input 1:
3
1 3
2 5
3 6
Sample Output 1:
1
3
Sample Input 2:
4
4 7
1 3
2 5
5 6
Sample Output 2:
2
3 6
Memory Limit: 256 MB
Time Limit: 1 seconds