Editorial for Mock CCC '19 Contest 2 J3 - Tudor Buys Some Tea
Submitting an official solution before solving the problem yourself is a bannable offence.
To solve the subtask, note that Tudor will not be able to get any free tea. Therefore, the answer is .
To solve the problem, we need to compute the maximum number of free cups of tea that Tudor can obtain. If we think about "bundles" of cups of tea, where Tudor buys cups of tea and gets one cup of free tea, we note that Tudor can get exactly bundles, which is exactly how many cups of free tea he can get. Therefore, the answer is .