Take and array and remove the first element, keep the next one, remove the third and continue in that way until you have only one element in the array, example:
start with [1,2,3,4,5,6]
remove 1, keep 2, remove 3, keep 4, remove 5, keep 6, remove 2, keep 4, remove 6, then return 4.
- remover [1,2,3] => 2
- remover [1,2,3,4] => 4