Google Sheet color rows 2 by 2

I cannot seem to find a way on how to color 2 rows in a row. All tutorials are to color alternating rows.

Namely, this is the situation

A1:O1 Header TitleA2:02 Header SubtitleA3:O3 NameA4:O4 ValueA5:O5 NameA6:O6 ValueA7:O7 NameA8:O8 Value...

Title rows are colored manually.I need to color rows 3 and 4 in 1 color, rows 5 and 6 in another color. Then again rows 7 and 8 in the first color. And so on.

Any ideas what custom formula in the conditional formatting should be?

I cannot use unique formula as nothing is unique here.