Codeforces Round 316 (Div. 2)
C
Replacement
Codeforces
1600
原题
← BD →
翻译中…

Daniel has a string $*s*$, consisting of lowercase English letters and period signs (characters '.'). Let's define the operation of replacement as the following sequence of steps: find a substring ".." (two consecutive periods) in string $*s*$, of all occurrences of the substring let's choose the first one, and replace this substring with string ".". In other words, during the replacement operation, the first two consecutive periods are replaced by one. If string $*s*$ contains no two consecutive periods, then nothing happens.

翻译中…

Let's define $*f*(*s*)$ as the minimum number of operations of replacement to perform, so that the string does not have any two consecutive periods left.

翻译中…

You need to process $*m*$ queries, the $*i*$-th results in that the character at position $*x*_{*i*}$ ($1 ≤ *x*_{*i*} ≤ *n*$) of string $*s*$ is assigned value $*c*_{*i*}$. After each operation you have to calculate and output the value of $*f*(*s*)$.

翻译中…

Help Daniel to process all queries.

翻译中…

Input

翻译中…

The first line contains two integers $*n*$ and $*m*$ ($1 ≤ *n*, *m* ≤ 300 000$) the length of the string and the number of queries.

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The second line contains string $*s*$, consisting of $*n*$ lowercase English letters and period signs.

翻译中…

The following $*m*$ lines contain the descriptions of queries. The $*i*$-th line contains integer $*x*_{*i*}$ and $*c*_{*i*}$ ($1 ≤ *x*_{*i*} ≤ *n*$, $*c*_{*i*}$ — a lowercas English letter or a period sign), describing the query of assigning symbol $*c*_{*i*}$ to position $*x*_{*i*}$.

翻译中…

Output

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Print $*m*$ numbers, one per line, the $*i*$-th of these numbers must be equal to the value of $*f*(*s*)$ after performing the $*i*$-th assignment.

翻译中…

Note

翻译中…

Note to the first sample test (replaced periods are enclosed in square brackets).

翻译中…

The original string is ".b..bz....".

翻译中…
  • after the first query $*f*($hb..bz....$)$ = 4 ("hb[..]bz...." $→$ "hb.bz[..].." $→$ "hb.bz[..]." $→$ "hb.bz[..]" $→$ "hb.bz.")
  • after the second query $*f*($hbс.bz....$)$ = 3 ("hbс.bz[..].." $→$ "hbс.bz[..]." $→$ "hbс.bz[..]" $→$ "hbс.bz.")
  • after the third query $*f*($hbс.bz..f.$)$ = 1 ("hbс.bz[..]f." $→$ "hbс.bz.f.")
翻译中…

Note to the second sample test.

翻译中…

The original string is ".cc.".

翻译中…
  • after the first query: $*f*($..c.$)$ = 1 ("[..]c." $→$ ".c.")
  • after the second query: $*f*($....$)$ = 3 ("[..].." $→$ "[..]." $→$ "[..]" $→$ ".")
  • after the third query: $*f*($.a..$)$ = 1 (".a[..]" $→$ ".a.")
  • after the fourth query: $*f*($aa..$)$ = 1 ("aa[..]" $→$ "aa.")
翻译中…

样例

Input #1
10 3
.b..bz....
1 h
3 c
9 f
Output #1
4
3
1
InputCopy OutputCopy
Input #2
4 4
.cc.
2 .
3 .
2 a
1 a
Output #2
1
3
1
1
InputCopy OutputCopy
题目信息
题号
570C
时间限制
2 s
内存限制
256 MB
标签
构造
数据结构
模拟

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