AT_abc477_d.Masking Tape

There are $N$ squares arranged in a horizontal row, numbered square $1$ to square $N$ from left to right. Colors are represented by lowercase English letters.

Initially, the color of every square is a, and nothing is placed on any square.

You are given $Q$ queries; process them in the given order. Each query is of one of the following two types:

• 1 X : If no tile is placed on square $X$, place a tile on it; if a tile is placed on it, remove it.

• 2 C : Change the color of every square on which no tile is placed to $C$.

Find the color of each square after processing all queries (regardless of whether a tile is placed on it).

有 $N$ 个正方形水平排列成一行，从左到右依次编号为正方形 $1$ 至正方形 $N$。颜色用小写英文字母表示。

初始时，每个正方形的颜色均为 a，且没有任何方块放置在任何正方形上。

给定 $Q$ 个查询，请按顺序处理它们。每个查询属于以下两种类型之一：

• 1 X ：若正方形 $X$ 上未放置方块，则在其上放置一个方块；若已放置方块，则将其移除。

• 2 C ：将所有未放置方块的正方形的颜色更改为 $C$。

请输出处理完所有查询后，每个正方形的颜色（无论其上是否放置了方块）。

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

$N$ $Q$
$\mathrm{query}_1$
$\vdots$
$\mathrm{query}_Q$

Each query $\mathrm{query}_i ~ (1 \le i \le Q)$ is given in the form

$1$ $X$

or

$2$ $C$

输入从标准输入中按以下格式给出：

$N$ $Q$
$\mathrm{query}_1$
$\vdots$
$\mathrm{query}_Q$

每个查询 $\mathrm{query}_i ~ (1 \le i \le Q)$ 的格式为

$1$ $X$

或

$2$ $C$

Output the final colors of the squares as a string of length $N$, concatenated from left to right.

以长度为 $N$ 的字符串形式输出方格的最终颜色，从左到右依次连接。

Sample 1 Explanation:
We represent the state of tiles as a string formed by concatenating, from left to right, # if a tile is placed and . otherwise.

The queries change the colors of the squares and the state of tiles as follows. The initial state is aaa and ....

• Processing the $1$-st query places a tile on square $2$. The state becomes aaa and .#..
• Processing the $2$-nd query changes the color of the squares without tiles to b. The state becomes bab and .#..
• Processing the $3$-rd query places a tile on square $1$. The state becomes bab and ##..
• Processing the $4$-th query removes the tile on square $2$. The state becomes bab and #...
• Processing the $5$-th query changes the color of the squares without tiles to c. The state becomes bcc and #...

Thus, output bcc. A tile remains placed on square $1$, but even in that case, output the color of the square.

Constraints

• $1 \le N,Q \le 3\times 10^5$
• Each query is of type $1$ or type $2$.
• In type-$1$ queries, $X$ is an integer satisfying $1 \le X \le N$.
• In type-$2$ queries, $C$ is a single lowercase English letter.

样例 1 解释：
我们将瓷砖的放置状态表示为一个字符串，该字符串通过从左到右拼接得到：若某方格上放置了瓷砖，则对应字符为 #；否则为 .。

各查询依次改变方格的颜色及瓷砖的放置状态，初始状态为 aaa 和 ...。

• 执行第 $1$ 个查询，在第 $2$ 个方格上放置一块瓷砖。状态变为 aaa 和 .#.。
• 执行第 $2$ 个查询，将所有未放置瓷砖的方格颜色改为 b。状态变为 bab 和 .#.。
• 执行第 $3$ 个查询，在第 $1$ 个方格上放置一块瓷砖。状态变为 bab 和 ##.。
• 执行第 $4$ 个查询，移除第 $2$ 个方格上的瓷砖。状态变为 bab 和 #..。
• 执行第 $5$ 个查询，将所有未放置瓷砖的方格颜色改为 c。状态变为 bcc 和 #..。

因此，输出 bcc。尽管第 $1$ 个方格上仍放置着瓷砖，但输出的仍是该方格的颜色。

约束条件

• $1 \le N,Q \le 3\times 10^5$
• 每个查询为类型 $1$ 或类型 $2$。
• 在类型 $1$ 的查询中，$X$ 是满足 $1 \le X \le N$ 的整数。
• 在类型 $2$ 的查询中，$C$ 是一个小写英文字母。