A10505. Vasiliy's Multiset

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 $A$ .

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 .