https://www.codewars.com/kata/simple-beads-count
Two red beads are placed between every two blue beads. There are N blue beads. After looking at the arrangement below work out the number of red beads.
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Implement count_red_beads(n) (in PHP count_red_beads($n); in Java, Javascript, C, C++ countRedBeads(n)) so that it returns the number of red beads.
If there are less than 2 blue beads return 0.