Virtual Memory - General Questions

How many page faults occur with LRU page replacement and 4 initially empty frames for the reference string: 6, 3, 1, 5, 4, 0, 1, 4, 3, 0

How many page faults occur with LRU page replacement and 3 initially empty frames for the reference string: 5, 3, 2, 0, 3, 5, 4, 1, 5, 6, 3, 3, 0, 3

Demand paging means:

How many page faults occur with Optimal page replacement and 4 initially empty frames for the reference string: 6, 2, 3, 2, 4, 5, 2, 5, 0, 0

How many page faults occur with Optimal page replacement and 3 initially empty frames for the reference string: 5, 1, 5, 1, 1, 0, 1, 3, 6, 3, 4