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 (GNU Fortran 9.2.1) (judge verdict: Accepted)

program sample
    implicit none
    character(100)::s
    integer(8) :: i,j,m,n,a,b
    integer(8),allocatable :: x(:),y(:)
  
    read(*,*) s
    allocate(x(26))
    n=len_trim(s)
    x(:)=0
    do i=1,n
        a=ichar(s(i:i))-96
        x(a)=x(a)+1
    end do
    if(maxval(x)>1)then
        write(*,*)'no'
    else
        write(*,*)'yes'
    end if
  
    stop
end program sample