Smallest Substring Containing All Unique Characters

Given a string S, find the length of the smallest substring that contains every unique character present in S. In other words, if the set of unique characters in S is \( U = \{u_1, u_2, \dots, u_k\} \), determine the minimum length \( L \) such that there exists a substring of S which includes every character from \( U \).

Example:

• For S = "abac", the smallest substring is "bac" and hence the answer is 3.
• For S = "aaaa", the unique character is just "a", so the answer is 1.

Your task is to implement a function that reads input from stdin and writes the result to stdout.

inputFormat

The input consists of a single line containing the string S (without spaces).

Input Format:

S

outputFormat

Output a single integer representing the minimum length of a substring of S that contains all unique characters present in S.

Output Format:

L

## sample

abac

3