Vasiliy's Multiset

``` 有q次操作和一个集合A，开始时集合中只有一个数0，下面有三种类型的操作： 1. + x 把x插入集合A 2. - x 把x从集合A中删去，保证x已存在于集合A中 3. ? x 给一个数x在集合A中找一个y使得x^y最大，并求出这个值 数据范围:$1\leq q\leq 200000$ $1\leq x_i\leq10^9$ ```

Author has gone out of the stories about Vasiliy, so here is just a formal task description. You are given $ q $ queries and a multiset $ A $ , initially containing only integer $ 0 $ . There are three types of queries: 1. "+ x" — add integer $ x $ to multiset $ A $ . 2. "- x" — erase one occurrence of integer $ x $ from multiset $ A $ . It's guaranteed that at least one $ x $ is present in the multiset $ A $ before this query. 3. "? x" — you are given integer $ x $ and need to compute the value , i.e. the maximum value of bitwise exclusive OR (also know as XOR) of integer $ x $ and some integer $ y $ from the multiset $ A $ . Multiset is a set, where equal elements are allowed.

The first line of the input contains a single integer $ q $ ( $ 1<=q<=200000 $ ) — the number of queries Vasiliy has to perform. Each of the following $ q $ lines of the input contains one of three characters '+', '-' or '?' and an integer $ x_{i} $ ( $ 1<=x_{i}<=10^{9} $ ). It's guaranteed that there is at least one query of the third type. Note, that the integer $ 0 $ will always be present in the set $ A $ .

For each query of the type '?' print one integer — the maximum value of bitwise exclusive OR (XOR) of integer $ x_{i} $ and some integer from the multiset $ A $ .

10
+ 8
+ 9
+ 11
+ 6
+ 1
? 3
- 8
? 3
? 8
? 11

11
10
14
13

After first five operations multiset $ A $ contains integers $ 0 $ , $ 8 $ , $ 9 $ , $ 11 $ , $ 6 $ and $ 1 $ . The answer for the sixth query is integer  — maximum among integers , , ,  and .