Codeforces Round 657 (Div. 2)
F2
Chess Strikes Back (hard version)
Codeforces
2800
原题
← F1→
翻译中…

Note that the difference between easy and hard versions is that in hard version unavailable cells can become available again and in easy version can't. You can make hacks only if all versions are solved.

翻译中…

Ildar and Ivan are tired of chess, but they really like the chessboard, so they invented a new game. The field is a chessboard $2n \times 2m$: it has $2n$ rows, $2m$ columns, and the cell in row $i$ and column $j$ is colored white if $i+j$ is even, and is colored black otherwise.

翻译中…

The game proceeds as follows: Ildar marks some of the white cells of the chessboard as unavailable, and asks Ivan to place $n \times m$ kings on the remaining white cells in such way, so that there are no kings attacking each other. A king can attack another king if they are located in the adjacent cells, sharing an edge or a corner.

翻译中…

Ildar would like to explore different combinations of cells. Initially all cells are marked as available, and then he has $q$ queries. In each query he either marks a cell as unavailable, or marks the previously unavailable cell as available. After each query he would like to know whether it is possible to place the kings on the available cells in a desired way. Please help him!

翻译中…

Input

翻译中…

The first line of input contains three integers $n$, $m$, $q$ ($1 \leq n, m, q \leq 200\,000$) — the size of the board and the number of queries.

翻译中…

$q$ lines follow, each of them contains a description of a query: two integers $i$ and $j$, denoting a white cell on the board ($1 \leq i \leq 2n$, $1 \leq j \leq 2m$, $i + j$ is even). If the cell $(i, j)$ was available before the query, then it becomes unavailable. Otherwise, if the cell was unavailable, it becomes available.

翻译中…

Output

翻译中…

Output $q$ lines, $i$-th line should contain answer for a board after $i$ queries of Ildar. This line should contain "YES" if it is possible to place the kings on the available cells in the desired way, or "NO" otherwise.

翻译中…

Note

翻译中…

In the first example case after the second query only cells $(1, 1)$ and $(1, 5)$ are unavailable. Then Ivan can place three kings on cells $(2, 2)$, $(2, 4)$ and $(2, 6)$.

翻译中…

After the third query three cells $(1, 1)$, $(1, 5)$ and $(2, 4)$ are unavailable, so there remain only 3 available cells: $(2, 2)$, $(1, 3)$ and $(2, 6)$. Ivan can not put 3 kings on those cells, because kings on cells $(2, 2)$ and $(1, 3)$ attack each other, since these cells share a corner.

翻译中…

样例

Input #1
1 3 3
1 1
1 5
2 4
Output #1
YES
YES
NO
InputCopy OutputCopy
Input #2
3 2 10
4 2
6 4
1 3
4 2
6 4
2 2
2 4
1 3
4 4
3 1
Output #2
YES
YES
NO
NO
YES
YES
NO
YES
YES
NO
InputCopy OutputCopy
题目信息
题号
1379F2
时间限制
2 s
内存限制
512 MB
标签
数据结构
分治

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。