$ZYB$ played a game named $Number Bomb$ with his classmates in hiking:a host keeps a number in $[1,N]$ in mind,then

players guess a number in turns,the player who exactly guesses $X$ loses,or the host will tell all the players that

the number now is bigger or smaller than $X$.After that,the range players can guess will decrease.The range is $[1,N]$ at first,each player should guess in the legal range.

Now if only two players are play the game,and both of two players know the $X$,if two persons all use the best strategy,and the first player guesses first.You are asked to find the number of $X$ that the second player

will win when $X$ is in $[1,N]$.

players guess a number in turns,the player who exactly guesses $X$ loses,or the host will tell all the players that

the number now is bigger or smaller than $X$.After that,the range players can guess will decrease.The range is $[1,N]$ at first,each player should guess in the legal range.

Now if only two players are play the game,and both of two players know the $X$,if two persons all use the best strategy,and the first player guesses first.You are asked to find the number of $X$ that the second player

will win when $X$ is in $[1,N]$.

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