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 Ruby (2.3.3) (judge verdict: Accepted)

line = gets
word = Hash.new
hoge = line.split("")
ans = "yes"
hoge.each{|var|
	if word[var] == nil
		word[var] = 1
		#p(word[var])
	else
		word[var] += 1
		#p(word[var])
	end
#print("#{var}\s")
}

word.each_value do |value|
	if value == 1
		ans = "yes"
		#p(value)
	else
		ans = "no"
		#p(value)
		break
	end
end

puts(ans)