Letters associated with prime numbers If we assign each letter a respective integer, starting from 1, then a is 1, b is 2, c is 3, and so on. After z, the letters loop back around, but with a in front (aa, ab, ac). It then goes to ba, bb, bc... After this is completed, as you may have figured, another letter is added (aaa, aab, aac).  "Prime letters" would be letters that are associated with a prime number. b would be the first prime letter, followed by c, e, g, et cetera. 

The Challenge

Given an input n, find the nth "prime letter."

Examples

Input:

1


Output:

b


Input:

4


Output:

g


Input:

123


Output:

za


Scoring Criteria

This is code golf, so the shortest answer in bytes wins!
Python 3,262 236 209 196 179 114 93 92  97 bytes



def f(n):
 m=k=1;s=''
 while n:m*=k*k;k+=1;n-=m%k
 while k:s=chr(~-k%26+97)+s;k=~-k//26
 return s


Try it online!

Fixed a bug mentioned by @benrg about getting a wrong output for the input 123.

Thanks to:
- @AdmBorkBork for help me getting started and save a few bytes
- @Sriotchilism O'Zaic for saving me 6 bytes
- @mypetlion for saving me 65 bytes and bringing me under 150 bytes :)
- @dingledooper for saving me 21 bytes and bringing me under 100 bytes :D
- @Jitse for saving 1 byte  



98 bytes



f=lambda n,i=1,p=1:n and-~f(n-p%i,i+1,p*i*i)
g=lambda n,s='':n and g(~-n//26,chr(~-n%26+97)+s)or s


Try it online!