new_contents: #!/usr/bin/python
  
  def check_isomorphic(s1, s2) :
   d = dict()
   if len(s1) != len(s2) :
    return False
   for i in range(0, len(s1)) :
    if s1[i] in d :
      if d[s1[i]] != s2[i] :
       return False
    else :
     if s2[i] in d.values() :
      return False
     d[s1[i]] = s2[i]
   return True
  
  s1 = raw_input("Enter first string : ")
  s2 = raw_input("Enter second string : ")
  
  is_isomorphic = check_isomorphic(s1, s2)
  if(is_isomorphic) :
   print "The srings are isomorphic"
  else :
   print "The strings are NOT isomorphic"
  
subject: Check if two strings are isomorphic