# Write a Python Set | Check whether a given string is Heterogram or not 
 # Function to Check whether a given string is Heterogram or not 
  
def heterogram(input):
  
     # separate out list of alphabets using list comprehension
     # ord function returns ascii value of character
     alphabets = [ ch for ch in input if ( ord(ch) >= ord('a') and ord(ch) <= ord('z') )]
  
     # convert list of alphabets into set and 
     # compare lengths
     if len(set(alphabets))==len(alphabets):
         print ('Yes')
     else:
         print ('No')
  
# Driver program
if __name__ == "__main__":
    input = 'the big dwarf only jumps'
    heterogram(input)