Find K’th Character of Decrypted String

You are given an encrypted string where repetitions of substrings are expressed as the substring followed by the count of these substrings. The task is to find the 'K'th character in the decrypted string. The decrypted string uses 1-based indexing.

Example:

The string "aabbbcdcdcd" is encrypted as "a2b3cd3".

Input:

S: The encrypted string.
K: An integer representing the position in the decrypted string you need to find.

Output:

The character at the 'K'th position of the decrypted string obtained from string 'S'.

Example:

Input:

S = "a2b3cd3", K = 5

Output:

'b'

Constraints:

• 2 <= N <= 10⁵
• 1 <= K <= M
• 1 <= M <= 10¹⁸

Where 'N' is the length of the encrypted string 'S', and 'M' is the length of the decrypted string from 'S'. All characters in string 'S' are lowercase English letters.

Note: You only need to implement the function as output has been handled. Also, the string will not contain any spaces, and each substring is followed by an integer indicating its frequency.