source_code: import java.util.Scanner;
  
  
  public class Prob023A
  {
      public static void main( String[] Args )
      {
          Scanner scan = new Scanner( System.in );
          String s = scan.next();
  
          all: for ( int x = s.length() - 1; x >= 0; x-- )
              for ( int y = 0; x + y <= s.length(); y++ )
              {
                  String sub = s.substring( y, y + x );
                  if ( s.indexOf( sub, y + 1 ) >= 0 )
                  {
                      System.out.println( x );
                      break all;
                  }
              }
      }
  }
  