Solved by ojc123004

#	Title	# Solved	Avg. Tries
25793	초콜릿 피라미드	312	3.32
26517	연속인가? ?	1,200	1.72
27866	문자와 문자열 STANDARD	55,783	1.48
27907	The primes contain arbitrarily long arithmetic progressions	425	2.88

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