source_code: 
  import java.util.Scanner;
  
  public class P23A {
      public P23A() {
          Scanner sc = new Scanner(System.in);
          String str = sc.next();
          sc.close();
          
          String maxStr = "";
          for (int i = 0; i < str.length() - 1; i++){
              for (int j = i + 1; j < str.length(); j++){
                  String pattern = str.substring(i, j);
                  if (str.substring(i+1).contains(pattern) && pattern.length() > maxStr.length()){
                      maxStr = pattern;
                  }
              }
          }
          System.out.println(maxStr.length());
      }
      
      public static void main (String []args){
          new P23A();
      }
  }
  