Tester's solution gives 3 on string ab and k = 2.How? Why?

This question is basically not very clear defined. Assuming too many conditions people know, which means this is not a good question.

I did not understand the test. I can only include a single caracterer in the string? Or can include more than one character?

That awkward situation when setter's code gets RUNTIME ERROR and upon fixing the array size, it gets TLE :P

for test case no 3 answer given is 104 how it is possible??