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: Wrong Answer)

n = gets.to_i
alphabets = []
("a".."z").each do |alphabet|
    alphabets << alphabet
end

a_26 = [0, 26]
loop do
    a_26 << a_26.last * 26 + a_26.last
    break if a_26.last > 1000000000000001
end

ruijo = 0
n.times do |i|
    if n <= a_26[i]
        ruijo = i + 1
        break
    end
end

# minus = ruijo - 3
# minus = 0 if minus < 0
# n -= a_26[minus]

str = ""
(0..(ruijo - 2)).each do |i|
    index = (n % 26) - 1
    n -= 1
    # puts index.to_s + " " + n.to_s
    str += alphabets[index].to_s
    n /= 26
    # puts index.to_s + " " + n.to_s
end
puts str.reverse