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 Julia (0.5.0) (judge verdict: Accepted)

parseInt(x::String) = parse(Int, x)
parseInt(x::SubString{String}) = parse(Int, x)
parseInt(x::Char) = parse(Int, x)
parseInt(x::Float64) = trunc(Int, x)
parseFloat(x::String) = parse(Float64, x)
parseFloat(x::Int) = trunc(Float64, x)
parseFloat(x::SubString{String}) = parse(Float64, x)
parseFloat(x::Char) = parse(Float64, x)
parseMap(x::Array{SubString{String},1}) = map(parseInt, x)

function main()
    s=join(sort(collect(chomp(readline()))))
    l=length(s)
    ans="yes"
    for i in 2:l
        if s[i]==s[i-1]
            ans="no"
        end
    end
    println(ans)
end
main()