source_code: import java.io.*;
  import java.util.Scanner;
  import java.lang.String;
  public class A23 {
      public static void main(String[] args) {
      Scanner in = new Scanner(System.in);
      String s = in.nextLine();
      int i=0,j=0,n=0,t=0,count=0;
      n=s.length();
      String s1="y",s2="yu6j";
      for(t=1;t<n;t++)
          {
          for(i=0;i<t;i++)
              {
              s1=s.substring(i,i+n-t);
              for(j=i+1;j<=t;j++)
                  {
                  s2=s.substring(j,j+n-t);
                  if(s1.equalsIgnoreCase(s2))
                      {
                      count++;break;
                      }
                  if(count==1) break;
                  }
              if(count==1) break;
              }
          if(count==1) break;
          }
  	if(n==0)
  		{
  	  System.out.println("0");
  		}
  	else
  	{
      if(count==1)
      {
      System.out.println(s1.length());
      }
      else  System.out.println("0");
      }
  	}
  }