Problem:
Score : 300 points

Problem Statement

1000000000000001 dogs suddenly appeared under the roof of Roger's house, all of which he decided to keep. The dogs had been numbered 1 through 1000000000000001, but he gave them new names, as follows:

the dogs numbered 1,2,\cdots,26 were respectively given the names a, b, ..., z;

the dogs numbered 27,28,29,\cdots,701,702 were respectively given the names aa, ab, ac, ..., zy, zz;

the dogs numbered 703,704,705,\cdots,18277,18278 were respectively given the names aaa, aab, aac, ..., zzy, zzz;

the dogs numbered 18279,18280,18281,\cdots,475253,475254 were respectively given the names aaaa, aaab, aaac, ..., zzzy, zzzz;

the dogs numbered 475255,475256,\cdots were respectively given the names aaaaa, aaaab, ...;

and so on.

To sum it up, the dogs numbered 1, 2, \cdots were respectively given the following names:

a, b, ..., z, aa, ab, ..., az, ba, bb, ..., bz, ..., za, zb, ..., zz, aaa, aab, ..., aaz, aba, abb, ..., abz, ..., zzz, aaaa, ...

Now, Roger asks you:

"What is the name for the dog numbered N?"

Constraints

N is an integer.

1 \leq N \leq 1000000000000001

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer to Roger's question as a string consisting of lowercase English letters.

Sample Input 1

2

Sample Output 1

b

Sample Input 2

27

Sample Output 2

aa

Sample Input 3

123456789

Sample Output 3

jjddja

Solution in Ruby (2.7.1) (judge verdict: Accepted)

#n,k=gets.split(' ').map(&:to_i)
#h=gets.split(' ').map(&:to_i)
#tajigen = Array.new(4) { Array.new(2,0) }
x=gets.to_i
serch_leng=1
serch_sum=0
while x>(26**serch_leng+serch_sum)
  serch_sum+=26**serch_leng
  serch_leng+=1
end
#puts serch_leng
x-=serch_sum
serch_start=+1
serch_end=serch_sum+26**serch_leng
#puts x
abc=('a'..'z').to_a
#puts abc
str=[]
#puts x
#puts serch_start
#puts serch_end
for i in 1..serch_leng
  #str.push(abc[x/26*i])
  count=0
  i_rever=serch_leng-i
  while x>26**i_rever*(count+1)
    count+=1
  end
  str.push(abc[count])
  #puts 26**i_rever*count
  x-=(26**i_rever*count)
  #puts x
end
puts str.join