Codeforces Round 556 (Div. 1)
B
Three Religions
Codeforces
2200
原题
← AC →
翻译中…

During the archaeological research in the Middle East you found the traces of three ancient religions: First religion, Second religion and Third religion. You compiled the information on the evolution of each of these beliefs, and you now wonder if the followers of each religion could coexist in peace.

翻译中…

The Word of Universe is a long word containing the lowercase English characters only. At each moment of time, each of the religion beliefs could be described by a word consisting of lowercase English characters.

翻译中…

The three religions can coexist in peace if their descriptions form disjoint subsequences of the Word of Universe. More formally, one can paint some of the characters of the Word of Universe in three colors: $1$, $2$, $3$, so that each character is painted in at most one color, and the description of the $i$-th religion can be constructed from the Word of Universe by removing all characters that aren't painted in color $i$.

翻译中…

The religions however evolve. In the beginning, each religion description is empty. Every once in a while, either a character is appended to the end of the description of a single religion, or the last character is dropped from the description. After each change, determine if the religions could coexist in peace.

翻译中…

Input

翻译中…

The first line of the input contains two integers $n, q$ ($1 \leq n \leq 100\,000$, $1 \leq q \leq 1000$) — the length of the Word of Universe and the number of religion evolutions, respectively. The following line contains the Word of Universe — a string of length $n$ consisting of lowercase English characters.

翻译中…

Each of the following line describes a single evolution and is in one of the following formats:

翻译中…
  • + $i$ $c$ ($i \in \{1, 2, 3\}$, $c \in \{\mathtt{a}, \mathtt{b}, \dots, \mathtt{z}\}$: append the character $c$ to the end of $i$-th religion description.
  • - $i$ ($i \in \{1, 2, 3\}$) – remove the last character from the $i$-th religion description. You can assume that the pattern is non-empty.
翻译中…

You can assume that no religion will have description longer than $250$ characters.

翻译中…

Output

翻译中…

Write $q$ lines. The $i$-th of them should be YES if the religions could coexist in peace after the $i$-th evolution, or NO otherwise.

翻译中…

You can print each character in any case (either upper or lower).

翻译中…

Note

翻译中…

In the first example, after the 6th evolution the religion descriptions are: ad, bc, and ab. The following figure shows how these descriptions form three disjoint subsequences of the Word of Universe:

翻译中…

image

翻译中…

样例

Input #1
6 8
abdabc
+ 1 a
+ 1 d
+ 2 b
+ 2 c
+ 3 a
+ 3 b
+ 1 c
- 2
Output #1
YES
YES
YES
YES
YES
YES
NO
YES
InputCopy OutputCopy
Input #2
6 8
abbaab
+ 1 a
+ 2 a
+ 3 a
+ 1 b
+ 2 b
+ 3 b
- 1
+ 2 z
Output #2
YES
YES
YES
YES
YES
NO
YES
NO
InputCopy OutputCopy
题目信息
题号
1149B
时间限制
3 s
内存限制
256 MB
标签
动态规划
模拟
字符串

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。