Score : $300$ points

问题陈述

你有一个空袋子。你将收到 $Q$ 个查询，这些查询必须按顺序处理。

有三种类型的查询。

• 1 x : 将一个写有整数 $x$ 的球放入袋子中。
• 2 x : 从袋子中取出一个写有整数 $x$ 的球并丢弃它。当给出这个查询时，保证袋子里有一个写有整数 $x$ 的球。
• 3 : 打印袋子中球上写的不同整数的数量。

以上为大语言模型 kimi 翻译，仅供参考。

Problem Statement

You have an empty bag. You are given $Q$ queries, which must be processed in order.

There are three types of queries.

• 1 x : Put one ball with the integer $x$ written on it into the bag.
• 2 x : Remove one ball with the integer $x$ written on it from the bag and discard it. It is guaranteed that the bag has a ball with the integer $x$ written on it when this query is given.
• 3 : Print the number of different integers written on the balls in the bag.

Constraints

• $1 \leq Q \leq 2 \times 10^{5}$
• $1 \leq x \leq 10^{6}$
• When a query of the second type is given, the bag has a ball with the integer $x$ written on it.
• There is at least one query of the third type.
• All input values are integers.

Input

The input is given from Standard Input in the following format:

$Q$

$\text{query}_1$

$\text{query}_2$

$\vdots$

$\text{query}_Q$

The $i$-th query $\text{query}_i$ is given in one of the following three formats:

$1$ $x$

$2$ $x$

$3$

Output

If there are $K$ queries of the third type, print $K$ lines. The $i$-th line $(1 \leq i \leq K)$ should contain the answer to the $i$-th query of the third type.

Sample Input 1

8
1 3
1 1
1 4
3
2 1
3
1 5
3

Sample Output 1

3
2
3

Initially, the bag is empty.

For the first query 1 3, a ball with the integer $3$ written on it enters the bag.

For the second query 1 1, a ball with the integer $1$ written on it enters the bag.

For the third query 1 4, a ball with the integer $4$ written on it enters the bag.

For the fourth query 3, the bag has balls with the integers $1, 3, 4$, so print $3$.

For the fifth query 2 1, a ball with the integer $1$ written on it is removed from the bag.

For the sixth query 3, the bag has balls with the integers $3, 4$, so print $2$.

For the seventh query 1 5, a ball with the integer $5$ written on it enters the bag.

For the eighth query 3, the bag has balls with the integers $3, 4, 5$, so print $3$.

Sample Input 2

8
1 2
1 2
3
2 2
1 4
1 4
2 2
3

Sample Output 2

1
1