You are given a string S consisting of lowercase English letters. Determine whether all the characters in S are different.
import math
import sys
def py():
    print("Yes")
def pn():
    print("No")
def iin():
    x = int(input())
    return x

neko = 1000
nya = 0
nuko = 0

s = input()
for a in range(len(s)-1):
    for b in range(a+1,len(s)):
        if s[a] == s[b]:
            pn()
            sys.exit()
py()
import math
def py():
    print("yes")
def pn():
    print("no")
def iin():
    x = int(input())
    return x

neko = 0
nya = 0
nuko = 0

s = input()
for a in range(len(s)-1):
    for b in range(a+1,len(s)):
        if s[a] == s[b]:
            neko = 1
if neko:
    pn()
else:
    py()