You are given a string that consists of $n$ characters between a–z. The positions of the string are indexed $1,2,\dots,n$ .
Your task is to process $m$ operations of the following types:
Change the character at positionktoxCheck if the substring from positionato positionbis a palindrome
The first input line has two integers $n$ and $m$ : the length of the string and the number of operations.
The next line has a string that consists of $n$ characters.
Finally, there are $m$ lines that describe the operations. Each line is of the form "1 $k$ $x$ " or "2 $a$ $b$ ".
For each operation 2, print YES if the substring is a palindrome and NO otherwise.
7 5 aybabtu 2 3 5 1 3 x 2 3 5 1 5 x 2 3 5· \n \n · · \n · · \n · · \n · · \n · · \n
YES NO YES\n \n \n