Sheldon has come up with a new language in which all words are made up of exactly $K$ Lowercase english Letters .

For example if $K=4$, then :

• words "aaaa", "abcc", "zdsa" belong to the language as they are made up of exactly $4$ Lowercase english letters
• words "aa", "abbbb", "abccc" don't belong as they are not made up of exactly 4 letters
• words "Abcd", "aabD" don't belong as letters 'A' and 'D' are not lowercase.

Now consider a K-dictionary that contains all the words of this new language in asscending order.  For example if K=3, the dictionary contains words "aaa", "aab", "aac" ... "aaz", "aba", "abb" ...  "abz", "aca" and so on.

Sheldon wants to translate "The roommate agreement" into this new language. The translation is done word by word as follows :

• If a word has position $P$ is the "Oxford English Dictionary", it translates to the word with position $P$ in the K-dictionary.
• For example if $K=3$, and a word has position $4$ in the "Oxford English Dictionary", it translates to "aad".

Clearly the above translation is a complex process and can't be done manually. So Sheldon asked his friend Howard for help. But as Sheldon always makes fun of him, Howard refused. So now you have to help Sheldon.

More formally you will be given two integers $K$ and $P$, You have to find the word with position $P$ in the K-dictionary. You have to do this for $T$ test cases.

Input : 

• First line of input contains $T$, denoting number of Test cases.
• First line of every test case contains two integers $K$ and $P$.

Output :

For every test case print the word with position $P$ in K-dictionary. If $P$ exceeds the size of the K-dictionary, print $-1$.

Answer of every test case should start in a seperate line.

Constraints :

• $1 \leq T \leq 10^5$
• $1 \leq K \leq 5*10^5$, Sum of K over all test cases does not exceed $5*10^5$
• $1 \leq P \leq 10^{18}$

Subtasks : 

$10$ points :

• $T=1$
• $1 \leq K \leq 4$

$90$ points :

• Original constraints