Lucky Queries

3000ms

262144K

Description:

Petya loves lucky numbers very much. Everybody knows that lucky numbers are positive integers whose decimal record contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya brought home string s with the length of n. The string only consists of lucky digits. The digits are numbered from the left to the right starting with 1. Now Petya should execute m queries of the following form:

switch l r — "switch" digits (i.e. replace them with their opposites) at all positions with indexes from l to r, inclusive: each digit 4 is replaced with 7 and each digit 7 is replaced with 4 (1 ≤ l ≤ r ≤ n);
count — find and print on the screen the length of the longest non-decreasing subsequence of string s.

Subsequence of a string s is a string that can be obtained from s by removing zero or more of its elements. A string is called non-decreasing if each successive digit is not less than the previous one.

Help Petya process the requests.

Input:

The first line contains two integers n and m (1 ≤ n ≤ 10⁶, 1 ≤ m ≤ 3·10⁵) — the length of the string s and the number of queries correspondingly. The second line contains n lucky digits without spaces — Petya's initial string. Next m lines contain queries in the form described in the statement.

Output:

For each query count print an answer on a single line.

Sample Input:

2 3
47
count
switch 1 2
count

Sample Output:

2
1

Sample Input:

3 5
747
count
switch 1 1
count
switch 1 3
count

Sample Output:

2
3
2

Note:

In the first sample the chronology of string s after some operations are fulfilled is as follows (the sought maximum subsequence is marked with bold):

In the second sample:

Informação

Provedor Codeforces

Código CF145E