ranked update & 3 new extreme challenges

I've made a subtle improvement to our ranked mode regarding answer validation. In the past, when entering wrong answers, all input boxes were highlighted as wrong in red. Even if they were potentially correct answers. I say "potentially" because some challenges can have multiple correct answers. Our validation mechanism evaluates the code with the provided answers on the server, the final answer determines whether your choice(s) are right or wrong. To make matters more clear, upon validating wrong answers, only the validation button will be highlighted as wrong in red:

Three new challenges of extreme difficulty have been added to codr's ranked mode. Two of these are related to interesting optimization problems, the third one is simple yet challenging. Below you can find a demo of the latter challenge, the key to solving it is to find a pattern, because the actual problem has a much larger value for i.

let i = 81;
let A = 0;
while (i-- > 0)
  if (((i / 9) >> 0) % 3 !== (i % 9) % 3)
    ++A
// A = ?

As of today we have 27 easy, 40 medium, 25 hard and 8 extreme challenges in ranked mode. Do note that these are merely templates, each time you play a unique problem is generated for you from this set. The number of combinations range in the thousands.