<tswett> learn \xd0\xa1\xd0\xa1\xd0\xa1\xd0\xa0 is the Russian way of writing USSR. They like to write U as \xd0\xa1 sometimes.

#!/usr/bin/python
s=set()
try:
 while True:
  l=raw_input()
  if l not in s:
   s.add(l)
   print(l)
except EOFError:
 pass