Highest high & lowest low

[cranmax]

Hello everybody,

The excel must obtain the max value of a list of values, the range of values where it looks change depending on a constant.

Exercise: a list of 30 random values in column A; on C1 a "constant" like 3, 5, 10, 15. On column B the MAX value of 3 (A1:A3), 5 (A1:A5), 10 (A1:A10) and 15 (A1:A15) previous values. So theoretically the "constant" 3 (looks from A3 to A1) must start at B3 but I prefer to start since the first value at A1.
The MIN, I suppose is the same but changing a little bit the formula.
Ask me any questions.

Thanks.

 

[cranmax]

Here is the excel: https://drive.google.com/file/d/0B_AmAVgJV-QWLXdFVmlidnlsVVk/view?usp=sharing