Tournament rounds

Problem

Marta has judged the fair's thumb wrestling tournament for twenty years, and her rule is simple. It is single elimination: each round, everyone still in plays in pairs and the winner of each pair moves on to the next. If a round has an odd number of players, one rests and moves on without playing.

Write a function that takes how many players there are (a whole number, 1 or more) and returns how many rounds it takes to have a single champion. With 5: the first round has two pairs and one rests, so 3 move on; the second has one pair and one rests, so 2 move on; the third is the final. That is 3 rounds. With 1 player there is already a champion: 0 rounds.

Examples

• The example

  5 → 3

• Eight, no one rests

  8 → 3

• Two, straight to the final

  2 → 1

• Six, odd in the second round

  6 → 3

• Nine, one more than eight

  9 → 4

Besides these, the challenge has hidden tests that are revealed when you submit your solution.

You start with this

def rounds(players):
    pass

function rounds(players) {
}