번호	제목
18981	Maximum Weighted Matching
18982	Period Sequence
18983	Chiaki Sequence Revisited
18984	RMQ Similar Sequence
18985	Lyndon Substring
18986	Turn Off The Light
18987	Time Zone
18988	Mall
18989	Product
18990	Keyboard
18991	Machine Learning
18992	Mosaic
18993	Permutation
18994	Homework
18995	Postcards
18996	Addition
18997	Coaches
18998	Pastry shop
18999	Rikka with Linker
19000	Rikka with Proper Fractions