Write a program to find starting index of a subsequence belongs to a given string (should be entered by user).
Ex:
User given string: Welcome to StudyKorner, have a good day
Now provide the subsequence to be matched:
etoSt

Output: 6  (as the first character of given subsequence have a index value 6 in the string provided by user)

Note: Subsequence is a part of a string in the same order as it was in original string.