{"trustable":true,"sections":[{"title":"","value":{"format":"MD","content":"Setting password is very important, especially when you have so many \"interesting\u0027\u0027 things in `F:\\TDDOWNLOAD`.\n\nWe define the safety of a password by a value. First, we find all the substrings of the password. Then we calculate the maximum length of those substrings which, at the meantime, is a palindrome. \n\nA palindrome is a string that will be the same when writing backwards. For example, `aba`, `abba`, `abcba` are all palindromes, but `abcab`, `abab` are not.\n\nA substring of $S$ is a continous string cut from $S$. `bcd`, `cd` are the substrings of `abcde`, but `acd`, `ce` are not. Note that `abcde` is also the substring of `abcde`.\n\nThe smaller the value is, the safer the password will be.\n\nYou want to set your password using the first $M$ letters from the alphabet, and its \nlength should be $N$. Output a password with the smallest value. If there are multiple \nsolutions, output the lexicographically smallest one.\n\nAll the letters are lowercase."}},{"title":"Input","value":{"format":"MD","content":"The first line has a number $T$ ($T\\leq 15$) , indicating the number of test cases.\n\nFor each test case, there is a single line with two integers $M$ and $N$, as described above. ($1 \\leq M \\leq 26$, $1 \\leq N \\leq 10^5$)"}},{"title":"Output","value":{"format":"MD","content":"For test case $X$, output `Case #X:` first, then output the best password."}},{"title":"Sample 1","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e2\n2 2\n2 3\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eCase #1: ab\nCase #2: aab\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}