- Time limit: 1.00 s
- Memory limit: 128 MB
Uolevi is in a forest. Given the coordinates of Uolevi and all trees in the forest, calculate how many trees Uolevi can see at the moment. Uolevi can see a tree if it's not directly behind another tree from Uolevi's location.
Input
The first line contains a single integer , the number of trees in the forest. Second line contains integers and denoting Uolevi's location in the forest. Next lines each contain two integers and , the locations of the trees in the forest.
There are no two trees sharing the same location, and Uolevi is not in the same location with a tree.
Output
Output the number of trees Uolevi can see.
Constraints
Example
Input:
4 1 -1 0 1 -2 3 3 -1 -1 3
Output:
3