Lexicographical problem

The little Lili likes to play with alphabet. One day, her brother gives her a present for her
birthday. He knows that Lili already learn to read. So, he wants to give Lili a challenge.

Given first N alphabets in lowercase. Then, she must arrange those letters into a word
with distinct letters. Her brother realized that there are so many words to construct with
those N letters. So, he decided to construct a smallest lexicographical order word (the
first word found in the dictionary). For example, the word ”budi” will be found first before word ”bumi”. Unfortunately, the Little Lili doesn’t understand about lexicographic.
She want to ask you a favor to help her.
input :
Input consists of 1 interger T, number of testcase. The next T lines contains an integer
N describing the number of alphabets given by her brother.
output :
Output should be expressed in format ”Case #X: Y” - X is number of testcase and Y is
the result of his brother challenge.
constrains :
1 ≤ T ≤ 100
1 ≤ N ≤ 26
input 1 :
output 1 :
Case #1: a
Case #2: ab
explain :
When N = 2, ab and ba is the possible combination and ab is the smallest lexicographical
word that his brother wants.
can you help me on this problem ?

For each testcase, print the first n alphabets.