Correction: the problem says "until each subset contains exactly one atom" — implies only when possible. But 64000 is not a power of 2 — so it never reaches 1. But since halving stops when size is 1, we assume: after n splits, size = 64000 / 2ⁿ. Set equal to 1: 2ⁿ = 64000 → n = log₂(64000). - Abu Waleed Tea