import fileinput
words = set() #NOTE: it is unordered but it doesn't affect the result
tokens = (token for line in fileinput.input() for token in line.split())
for op, word in zip(*[tokens]*2):
if op == '+':
words.add(word)
elif op == '-':
words.discard(word)
elif op == '?':
print(word, "Yes" if word in words else "No")
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