The N-th String from the End

Problem Description

Consider an arithmetic increasing sequence made entirely of lowercase English letters, where every string has a fixed length $L$, starting from $L$ copies of a and increasing by $1$ each step. For example, when $L = 3$, the sequence is aaa, aab, aac, ..., aaz, aba, abb, ..., abz, ..., zzz. The second string from the end of this sequence is zzy. For any given $L$, output the $N$-th string from the end of the corresponding sequence.

Input Format

One line gives two positive integers $L$ ($1 \leq L \leq 6$) and $N$ ($N \leq 10^5$).

Note: the data range has been changed!

Output Format

Output the $N$-th string from the end on one line. The problem guarantees such a string exists.

Sample Input

6 789

Sample Output

zzzyvr