program c171

implicit none
integer(16) :: n, m, l
integer :: i, j
character(len=12) :: a, b

read *, n

i = 0

do while (n > 26)
 i = i + 1
 m = mod(n,26)
 if (m == 0) then
   m = 26
 end if
  a(i:i) = char(96 + m)
  n = n - m
  n = n / 26
end do

a(i+1:i+1) = char(96 + n)

do j = 1, i+1
 b(j:j) = a(i+2-j:i+2-j)
end do

if (i+1 == 12) then
 print '(A12)', trim(adjustl(b))
else if (i+1 == 11) then
 print '(A11)', trim(adjustl(b))
else if (i+1 == 10) then
 print '(A10)', trim(adjustl(b))
else if (i+1 == 9) then
 print '(A9)', trim(adjustl(b))
else if (i+1 == 8) then
 print '(A8)', trim(adjustl(b))
else if (i+1 == 7) then
 print '(A7)', trim(adjustl(b))
else if (i+1 == 6) then
 print '(A6)', trim(adjustl(b))
else if (i+1 == 5) then
 print '(A5)', trim(adjustl(b))
else if (i+1 == 4) then
 print '(A4)', trim(adjustl(b))
else if (i+1 == 3) then
 print '(A3)', trim(adjustl(b))
else if (i+1 == 2) then
 print '(A2)', trim(adjustl(b))
else
 print '(A1)', trim(adjustl(b))
end if

end program c171