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Time limit 2000/4000/4000/4000 ms. Memory limit 65000/65000/65000/65000 Kb. Автор: Михаил Копачев, РГАТА. Phalanx-2• the castle standing at the leftmost vertical line, stands also in the lowest horizontal line (and beats it); • there is no gap between any two castles that separates the castle from the next or previous • selecting first left k castles we shall get a regular phalanx of the width k. The drawings below show four positions, two of which - those on the left are phalanxes, and those on the right are not. Position (c) is not a regular phalanx as the second (unbeaten) horizontal line separates the second and the third castles from the lower horizontal line (condition 2 of the above list is not satisfied). Position (d) is not a regular phalanx: if we take two left castles, they will not form a regular phalanx (condition 3 of the above list is not satisfied). Your task is to make a program that will use the specified number n to define the quantity of different arrangements for castles m, that will be phalanxes. For example, when n=3, it is possible to have only m=5 phalanxes (e1)-(e5) Input The input contains the only number n. Output Output must contain the only number - the answer. Limitations 0 < n ≤ 18
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