$ZYB$ 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 $[1,N]$.