Given a string 's'. The task is to find the smallest window length that contains all the characters of the given string at least one time.
For eg. A = “aabcbcdbca”, then the result would be 4 as of the smallest window will be “dbca”.

Example 1:

Input : "AABBBCBBAC"
Output : 3
Explanation : Sub-string -> "BAC"

Input : "aaab"
Output : 2
Explanation : Sub-string -> "ab"

Input : "GEEKSGEEKSFOR"
Output : 8
Explanation : Sub-string -> "GEEKSFOR"

Your Task:  
You don't need to read input or print anything. Your task is to complete the function findSubString() which takes the string  S as inputs and returns the length of the smallest such string.

Expected Time Complexity: O(256.N)
Expected Auxiliary Space: O(256)

Constraints:
1 ≤ |S| ≤ 10⁵
String may contain both type of English Alphabets.