Google OA 2024 - first subsequence question

write a program to check whether string A contains string B as a subsequence or not. you can change at most 1 character in string B except the first character
return the starting index of subsequence if found
else return -1

Ex -

1. A = abcbc
   B = cbe
   answer = 3 (1 based indexing)

2. A = lhs
   B = rhs
   answer = -1 (you cannot change first character of B)