Ethan's doing his very first programming assignment: implementing a
contains() function. This function takes two strings, A and B, and
returns true if A is a substring of B, and false otherwise.
Here's the algorithm that Ethan has come up with. Note that |A| denotes the length of A, and the individual characters of the strings are 1-indexed.
- Set i and j to each be equal to 1.
- If i > |A|, return
true. - If j > |B|, return
false. - If Ai = Bj, increment i and j by 1 each, and return to Step 2.
- If i = 1, increment j by 1, and return to Step 2.
- Set i to be equal to 1, and return to Step 2.
As the TA in charge of grading Ethan's assignment, this doesn't look quite
right to you. To make sure Ethan doesn't get any more credit than he deserves,
you'd like to find some inputs for which his algorithm returns false even
though it should return true.
The professor teaching this class has provided you with a half-written list of
test cases. In particular, it's a list of inputs for the A parameter, and
you're free to come up with your own inputs for the B parameter. For each
given string A, you want to find a string B that will cause Ethan's
algorithm to return the wrong output (false instead of true), if possible.
A will only contain uppercase alphabetic characters, and B must follow
the same constraint. The test cases shouldn't be too large, so B must also
contain at most 10,000 characters.
Input
Input begins with an integer T, the number of given strings. Then, T lines follow. Each line contains a single string, A.
Output
For the _i_th given string, print a line containing "Case #i: " followed by any valid string B that will cause Ethan's algorithm to return the wrong value, or "Impossible" if no such string exists.
Constraints
1 ≤ T ≤ 100
1 ≤ |A| ≤ 2,000
Explanation of Sample
In the first case, i and j will have these values in order the first 10 times the algorithm is at Step 2:
i j
---
1 1
2 2
1 2
1 3
1 4
1 5
2 6
3 7
4 8
1 8
Please note that other outputs for example cases 1 and 3 would also be accepted.