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: Time Limit Exceeded)

a = gets.to_i

b = 1
c = ""
d = 27
e = 703
f = 18279
g = 475255
h = 12356631
j = 321272407
k = 8353082557
m = 217180146457
n = 5646683807857
l = 146813779004283

if 1 <= a && a <= 26
  ("a".."z").each do |i|
    if a == b
      c << i
      break
    end
    b += 1
  end
end

if 27 <= a && a <= 702
  ("aa".."zz").each do |i|
    if a == d
      c << i
      break
    end
    d += 1
  end
end

if 703 <= a && a <= 18278
  ("aaa".."zzz").each do |i|
    if a == e
      c << i
      break
    end
    e += 1
  end
end

if 18279 <= a && a <= 475254
  ("aaaa".."zzzz").each do |i|
    if a == f
      c << i
      break
    end
    f += 1
  end
end

if 475255 <= a && a <= 1235630
  ("aaaaa".."zzzzz").each do |i|
    if a == g
      c << i
      break
    end
    g += 1
  end
end

if 1235631 <= a && a <= 321272406
  ("aaaaaa".."zzzzzz").each do |i|
    if a == h
      c << i
      break
    end
    h += 1
  end
end

if 321272407 <= a && a <= 8353082556
  ("aaaaaaa".."zzzzzzz").each do |i|
    if a == j
      c << i
      break
    end
    j += 1
  end
end

if 8353082557 <= a && a <= 217180146456
  ("aaaaaaaa".."zzzzzzzz").each do |i|
    if a == k
      c << i
      break
    end
    k += 1
  end
end

if 217180146457 <= a && a <= 5646683807856
  ("aaaaaaaaa".."zzzzzzzzz").each do |i|
    if a == m
      c << i
      break
    end
    m += 1
  end
end

if 5646683807857 <= a && a <= 146813779004282
  ("aaaaaaaaaa".."zzzzzzzzzz").each do |i|
    if a == n
      c << i
      break
    end
    n += 1
  end
end

if 146813779004283 <= a && a <= 3817158254111358
  ("aaaaaaaaaaa".."zzzzzzzzzzz").each do |i|
    if a == l
      c << i
      break
    end
    l += 1
  end
end

puts c