Find the third and fourth non-blank cells in a column and then enter each result in a cell

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Hello All,
I have been on numerous websites all day but have not been successful in finding the answer to my problem.

Problem:
I need help to find the third and fourth non-blank cell in a range in, see attachment.
In range E12:E61, there are a series of blank and non-blank cells.
I need a formula to find the third non-blank cell, which in this example is M5-M5 and then enter the result, M5-M5, in cell E2
Similarly, I need a formula to find the fourth non-blank cell, which in this example is M7-M7 and then enter the result, M7-M7 in cell E4.
Now all the cells in range E12:E61 have formulas in them so the third and fourth non-blank cell could change depending on other conditions.

Any help would be appreciated.