#include <iostream>
#include <unordered_map>
#include <unordered_set>
#include <string>
#include <climits>
 
using namespace std;
 
int minSubstringWithAllUniqueChars(const string& s) {
    int n = s.length();
    unordered_set<char> uniqueChars(s.begin(), s.end());  // Get all unique characters in the string
    int required = uniqueChars.size();  // Number of unique characters needed in the substring
 
    unordered_map<char, int> windowCounts;
    int left = 0, right = 0, formed = 0;
    int minLength = INT_MAX;
 
    while (right < n) {
        char c = s[right];
        windowCounts[c]++;
 
        if (windowCounts[c] == 1) {  // If this character is part of the required unique characters
            formed++;
        }
 
        while (left <= right && formed == required) {
            // Update the minimum length
            minLength = min(minLength, right - left + 1);
 
            char leftChar = s[left];
            windowCounts[leftChar]--;
            if (windowCounts[leftChar] == 0) {
                formed--;
            }
            left++;
        }
        right++;
    }
 
    return minLength;
}
 
int main() {
    string s;
    cin >> s;
    cout << minSubstringWithAllUniqueChars(s) << endl;
    return 0;
}