please change the wording of the statement:
"there should be at most k Rocks of pairwise different colors among the Rocks taken from the Cave" would be much better read if it is changed to "there should be at most k Rocks of different colors among the Rocks taken from the Cave."

in other words, the word 'pairwise' should be removed to make the statement clear.

Edited by author 14.01.2015 05:20

Edited by author 14.01.2015 05:21