program main
  implicit none
  integer::N,i,keta
  integer::num(12)
  read *,N
  keta = 1
  do
     num(keta) = MOD(N,26)
     N = N/26
     if(N.eq.0) exit
     keta = keta + 1
  end do
  do i=keta,2,-1
     write(*,'(a)',advance='no') CHAR(ICHAR('A')+num(i)-1)
  end do
  write(*,'(a)',advance='yes') CHAR(ICHAR('A')+num(1))
end program main