#937. Activity selection
You get the start and end times of n activities. Choose the largest number of activities that do not overlap (one may start at the moment another ends). Print that number.
### Input
n, then n lines `s e`.
### Output
A number.
Examples
Input
5 12 15 11 13 19 20 16 20 13 16
Output
3
Input
5 17 21 11 17 12 16 14 17 12 17
Output
2
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.