CF79D Password

Finally Fox Ciel arrived in front of her castle! She have to type a password to enter her castle. An input device attached to her castle is a bit unusual. The input device is a $ 1×n $ rectangle divided into $ n $ square panels. They are numbered $ 1 $ to $ n $ from left to right. Each panel has a state either ON or OFF. Initially all panels are in the OFF state. She can enter her castle if and only if $ x_{1} $ -th, $ x_{2} $ -th, $ ... $ , $ x_{k} $ -th panels are in the ON state and other panels are in the OFF state. She is given an array $ a_{1} $ , $ ... $ , $ a_{l} $ . In each move, she can perform the following operation: choose an index $ i $ ( $ 1

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One possible way to type the password in the first example is following: In the first move, choose 1st, 2nd, 3rd panels and flip those panels. In the second move, choose 5th, 6th, 7th, 8th, 9th panels and flip those panels.