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 ABC171_C
  character(11)::B
  integer(16)::N,cnt=1,i,j
  integer(16),allocatable::C(:)
  read(*,*)N
  do i=1,11
     if(N>26**i) then
        N=N-26**i
        cnt=cnt+1
     else
        allocate(C(cnt))
        C=97
        do j=1,cnt
           C(j)=mod(N,26)+C(j)-1
           if(C(j)==96) C(j)=122
           N=N/26
           if(N==0)  then
              if(cnt>1) then
                 do k=2,cnt
                    if(C(k)/=97) C(k)=C(k)+1
                 end do
              end if
              exit
           end if
        end do
        exit
     end if
  end do
  do i=1,cnt
     B(cnt+1-i:cnt+1-i)=char(C(i))
  end do
  B=adjustl(B)
  B=trim(B)
  write(*,'(a)')B
end program ABC171_C