Given an ASCII string S1 and a substring S2 to search in. Find starting index in the target string S1 of first S2 occurence regardless of the character sequence. The complixity should be close to O(N * Log(M)).

Example: S1 = 'abc178965fdssa', S2 = '689' --> Index = 5

Test set 1

Result:

Test set 2

Result:

Test set 3

Result: