DYNACON1 - Dynamic Tree Connectivity

题目描述 给出一个森林，初始时有$N$个点，没有边。森林中的边是双向的。你需要支持以下操作： **add A B**：连接$A\ B$两点，保证连接完成后仍是森林。 **rem A B**：断开连接在$A\ B$之间的边，保证边存在。 **conn A B**：询问$A\ B$之间是否存在路径。 输入格式 第一行两个正整数$N,M(1 \leq N , M \leq 10^5)$ 接下来$M$行每行一个操作 输出格式 对于每一个**conn**操作输出一行，如果存在路径输出`YES`，否则输出`NO`

A forest of unrooted trees initially consists of N (1 Your task is to maintain that forest and answer connectivity queries. All edges in the problem are **undirected**. You will receive the following queries, where (1 - **add** A B : add an edge between vertices A and B, where initially there is no path between A and B. - **rem** A B : remove edge between vertices A and B, where initially there is an edge between A and B. - **conn** A B : print **YES** if there is a path between A and B and **NO** otherwise, where A and B are different.

The first line of input contains the number of initial single-vertex trees N and the number of queries M (1

For each **conn** query output **YES** or **NO**. Pay attention to letter case.

5 11
conn 1 5
add 1 2
add 1 3
add 3 4
add 5 4
conn 1 5
rem 4 5
conn 1 5
rem 3 4
add 3 5
conn 1 5

NO
YES
NO
YES