source_code: import java.util.*;
  
  public class Solution
  {
      public static void main(String[] args)
      {
          new Solution().calc();
      }
  
      void calc()
      {
          Scanner cin = new Scanner(System.in);
          String s = cin.next();
          int ret = 0;
          for (int i = 0; i < s.length(); i++)
          {
              for (int j = i + 1; j < s.length(); j++)
              {
                  for (int k = 0; j + k < s.length(); k++)
                  {
                      if (s.charAt(i + k) != s.charAt(j + k)) break;
                      ret = Math.max(k + 1, ret);
                  }
              }
          }
          System.out.println(ret);
      }
  }
  