#include <stdio.h>
#include <string.h>
#include <limits.h>
 
#define MAX_CHARS 26 // Assuming lowercase English letters only
 
int min_substring_length(char *s) {
    int n = strlen(s);
    int freq[MAX_CHARS] = {0}; // Array to store frequency of characters
    int unique_count = 0;
    int min_length = INT_MAX;
    int left = 0;
 
    // Count the number of unique characters
    for (int i = 0; i < n; i++) {
        if (freq[s[i] - 'a'] == 0)
            unique_count++;
        freq[s[i] - 'a']++;
    }
 
    // Sliding window approach
    for (int right = 0; right < n; right++) {
        freq[s[right] - 'a']--;
 
        while (unique_count == 0) {
            min_length = (right - left + 1) < min_length ? (right - left + 1) : min_length;
            freq[s[left] - 'a']++;
            if (freq[s[left] - 'a'] == 1)
                unique_count++;
            left++;
        }
    }
 
    return min_length;
}
 
int main() {
    char s[100001];
    scanf("%s", s);
    printf("%d\n", min_substring_length(s));
    return 0;
}