source_code: /**
   * MxNINJA 04:06:52 ص 14/01/2014
   */
  import java.io.BufferedReader;
  import java.io.InputStreamReader;
  
  public class Main {
  
      public static void main(String[] args) throws Exception {
          BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
          StringBuilder line = new StringBuilder(reader.readLine());
          int length = 0;
          for (int head = 0; head < line.length(); head++) {
              for (int tail = line.length() - 1; tail > head; tail--) {
                  String subString = line.substring(head, tail);
                  if(line.indexOf(subString,head+1)>-1){
                      length = Math.max(subString.length(), length);
                  }
              }
          }
          System.out.println(length);
      }
  }