import java.util.*;

public class Main {

	public static int solution(String str){
		int ans = Integer.MAX_VALUE;
		HashSet<Character> set1 = new HashSet<>();
		
		for(int i = 0 ;i < str.length();i++){
		    char ch = str.charAt(i);
		    
		    if(set1.contains(ch)==false)
		    set1.add(ch);
		}
		
		
		HashMap<Character,Integer> set2 = new HashMap<>();
		int i = -1 ;
		int j = -1 ;
		
		while(true){
		    boolean f1 = false;
		    boolean f2 = false;
		    
		    //accquire
		    while(j < str.length()-1 && set2.size() < set1.size() ){
		        j++;
		        char ch = str.charAt(j);
		        
		        set2.put(ch , set2.getOrDefault(ch,0)+1);
		        
		        f1 = true;
		    }
		    
		    //store ans and release
		    while(i < j && set2.size() == set1.size() ){
		     String pans = str.substring(i+1 , j+1);
		     
		     if(pans.length() < ans)
		     ans = pans.length();
		     
		     i++;
		     
		     char ch = str.charAt(i);
		    
		        if(set2.get(ch) ==1)
		        set2.remove(ch);
		        
		        else
		        set2.put(ch , set2.getOrDefault(ch,0)-1);
		     
		     
		     f2 = true;   
		    }
		    
		    if(f1 == false && f2 == false)
		    break;
		}
		
		return ans;
	}
	
	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
		String str = scn.next();
		System.out.println(solution(str));
	}

}