ALDS1_4_C: Dictionary - sinapusu2002 @ ウィキ

http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_4_C
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# your code goes here
require 'set'
hs=Set.new()
n=STDIN.gets.to_i

n.times do |i|
com,str=STDIN.gets.split(" ")
case com
when "insert"
	hs.add(str)
when "find"
	if hs.include?(str)
		puts "yes"
	else
		puts "no"
	end
end
end