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 Fortran (GNU Fortran 9.2.1) (judge verdict: Wrong Answer)

program main
    use iso_fortran_env
    implicit none

    integer(int64) :: n
    integer(int64) :: i, m, k, left, right
    character(1),allocatable :: name(:)
    character(26) :: alp
    alp = "zabcdefghijklmnopqrstuvwxy"

    read(*,*) n

    i = 0
    left = 0
    right = 0

    do
        left = left + (26**(i) * 1)
        right = right + (26**(i) * 26)
        if ( (left <= n).and.(n <= right) ) then
            exit
        endif
        i = i + 1
!        print *, i, left, right
    enddo
    allocate(name(0:i))

    do k = 0, i
        m = mod(n, 26)
        name( i - k ) = alp(m+1:m+1)
        n = int( (n-1) / 26)
    enddo
    print *, name

end program main