DYNACON2  Dynamic Graph Connectivity
A graph initially consists of N (1 ≤ N ≤ 100,000) unconnected vertices. The vertices are numbered from 1 to N.
Your task is to maintain that graph and answer connectivity queries.
All edges in the problem are undirected.
You will receive the following queries, where (1 ≤ A, B ≤ N) :
 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.
Input
The first line of input contains the number of vertices N and the number of queries M (1 ≤ M ≤ 100,000). The following M lines contain queries.
Output
For each conn query output YES or NO. Pay attention to letter case.
Example
Input:
4 11
add 1 2
add 2 3
add 3 4
add 1 4
conn 4 2
rem 1 2
conn 2 4
rem 3 4
conn 4 2
add 2 4
conn 4 2
Output:
YES
YES
NO
YES
This example will be the first test case.
hide comments
petkov:
20190301 17:54:05
The constrains are not too tight. I solved it with segment tree + partially persistent dsu. You don't need link/cut trees. 

tanavya:
20171208 20:25:29
TLE :( constraints too tight. 

dacin21:
20160110 20:52:26
For those who want a challenge, one can actually solve this problem using an online algorithm (answer each querry before you read the next one)! Because that's what i did. 

immortalco:
20151004 10:54:46
The problem description is wrong.


immortalco:
20151004 10:52:58
A tough task.


jkelava6:
20150104 14:09:10
"where initially there is no path between A and B"  but first 4 commands of the example form a square. "add 1 4" breaks that rule! Please fix! Last edit: 20150104 14:22:13 
Added by:  indy256 
Date:  20110922 
Time limit:  2s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 