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: Runtime Error)

N = gets.to_i
s = N
alp = ('a'..'z').to_a
i = 1
while s > 26*(26**i-1)/25 do
  i += 1
end
#iは２６進数におけるNの桁数である
gift = []
while i > 1 do
  ary = s.divmod(26**(i-1))
  if ary[1] == 0 && ary[0] != 1 then
    ary[0] -= 1
    ary[1] = 26**(i-1)
  end
  gift.push(ary[0])
  s = ary[1]
  i -= 1
end
if 0<s && s<27 then
  gift.push(s)
else
  gift.push(ary[1])
end
print alp[gift[0]-1]
print alp[gift[1]-1]
print alp[gift[2]-1]
print alp[gift[3]-1]
print alp[gift[4]-1]
print alp[gift[5]-1]
print alp[gift[6]-1]
print alp[gift[7]-1]
print alp[gift[8]-1]
print alp[gift[9]-1]
print alp[gift[10]-1]
print alp[gift[11]-1]