70584
Cm and Es may still be usable as targets , allowing the production of isotopes with one or two more neutrons than known isotopes , though the production of several milligrams of these rare isotopes to create a target is difficult .
 Es
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Es