## 题目

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I’ll tell you whether the number is higher or lower.

You call a pre-defined API `guess(int num)`

which returns 3 possible results (`-1`

, `1`

, or `0`

):

-1 : My number is lower

1 : My number is higher

0 : Congrats! You got it!

**Example:**

n = 10, I pick 6.

Return 6.