Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters. Determine whether all the characters in S are different.

Constraints

2 ≤ |S| ≤ 26, where |S| denotes the length of S.

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If all the characters in S are different, print yes (case-sensitive); otherwise, print no.

Sample Input 1

uncopyrightable

Sample Output 1

yes

Sample Input 2

different

Sample Output 2

no

Sample Input 3

no

Sample Output 3

yes

Solution in Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program varied
  implicit none
  character(26) :: s
  integer       :: n, i, m(26), c
  read(*,*) s
  s = adjustl(s)
  n = len_trim(s)
  m = 0
  do i = 1, n
    c = ichar(s(i:i)) - 96
    m(c) = m(c) + 1
  end do
  if (maxval(m) > 1) then
    write(*,'(a)') "no"
  else
    write(*,'(a)') "yes"
  end if
end program varied