def min_substring_length(s):
    n = len(s)
    unique_chars = set(s)
    freq = {}
    unique_count = 0
    min_length = float('inf')
    left = 0
 
    for right in range(n):
        if s[right] not in freq:
            freq[s[right]] = 0
        freq[s[right]] += 1
 
        if freq[s[right]] == 1:
            unique_count += 1
 
        while unique_count == len(unique_chars):
            min_length = min(min_length, right - left + 1)
            freq[s[left]] -= 1
            if freq[s[left]] == 0:
                unique_count -= 1
            left += 1
 
    return min_length
 
# Test the function
s = input().strip()
print(min_substring_length(s))