In small fit there lives a hare. Jumping out of a hole and running on snow, it left traces. To define where there is a hare. The input data the Card of driving of a hare is set N (1<=N<=100) by lines which contain sequence of capital Latin letters the first letter whence the following where. Output data Deduce sequence of letters in a column in ascending order which specify a possible location of a hare if the card cannot be driving of a hare to deduce NO SOLUTION. An example 10 B C D K M A C D K L D L R K L Q N M M N A A P N N P Q P R L L R R P Answer B L the Question, whether the understanding of an example that is correct: 1) the way part is B-> C-> D-> K-> M-> A-> P-> R-> L-> Q-> N | |--------------- 2) "Deduce sequence of letters... In ascending order" - means, what topological sorting where L receives smaller number, than And though both peaks are in one cycle beforehand is fulfilled? 3) NO SOLUTION - the answer when there is no way on which it is possible to transit all peaks (in an example - quitting from In it is possible to visit all peaks)?