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

Example 3:
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 input and returns the length of the smallest such window of the string.
Expected Time Complexity: O(256.N)
Expected Auxiliary Space: O(256)

Constraints:
1 ≤ |S| ≤ 10^{5}
String may contain both type of English Alphabets.

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