Molecules with Potassium

As you may know, potassium has as chemical symbol K; only one other element has a K in its symbol, namely, krypton Kr, a noble gas that hardly ever participates in a molecule.

Your program must process a sequence of molecules, given by their formulas, and none of which contains Kr. Your program should ignore all molecules not containing potassium and, of the rest, it must report the most frequent formula(s) among those coming in the sequence before the first occurrence of NaCl (which is ignored from the counting as it does not have K but, of course, is not ignored as an endmark).

Input

Input is a sequence of molecules. There is no information about whether they are organized in lines nor, if so, how. It is guaranteed that there is at least one occurrence of the molecule NaCl and that, before it, there is at least one occurrence of some molecule containing potassium.

Output

Your program must write the most frequent molecule found in the sequence before the first occurrence of NaCl, under the condition that only molecules including potassium are to be considered. Molecules without potassium are to be ignored, except for the endmarker NaCl. In case of a tie, your program must output all the tied molecules, ordered from smaller ones to larger ones according to Python3’s str ordering. All molecules printed out must be each on a line with no extra spaces or lines.

Problem information

Author: José Luis Balcázar

Generation: 2026-01-25T17:01:32.693Z