PROGRAMMING:Penultimate string
Given a string isochromatic incremental sequence composed of lowercase English letters, the length of each string in the sequence is fixed as l, starting from L A, and increasing by 1. For example, when l is 3, the sequence is {AAA, AAB, AAC,..., aaz, ABA, abb,..., ABZ,..., zzz}. The penultimate string of this sequence is zyz. For any given L, this problem requires you to give the n-th string from the bottom of the corresponding sequence.
###Input format:
Input gives two positive integers L (2 $$$Le $$l $$$Le $$6) and n ($$$Le 10 ^ 5 $$) in one line.
###Output format:
Output the penultimate string of the corresponding sequence in one line. The title guarantees that the string exists.
###Input example:
```in
3 7417
```
###Output example:
```out
pat
```
answer：If there is no answer, please comment
###Input format:
Input gives two positive integers L (2 $$$Le $$l $$$Le $$6) and n ($$$Le 10 ^ 5 $$) in one line.
###Output format:
Output the penultimate string of the corresponding sequence in one line. The title guarantees that the string exists.
###Input example:
```in
3 7417
```
###Output example:
```out
pat
```
answer：If there is no answer, please comment