source_code: import java.util.*;
  import java.io.*;
  
  public class P1 {
  	public static void main(String[] args) {
  		String s = null;
  		// citire
  		try {
  //			Scanner sc = new Scanner(new File("in.txt"));
  			Scanner sc = new Scanner(System.in);
  			s = sc.next();
  			
  		}
  		catch (Exception e) {
  			e.printStackTrace();
  		}
  		
  		int n = s.length();
  		
  		HashSet<String> h = new HashSet<String>();
  		String t=null;
  		boolean b;
  		int lmax = 0;
  		for (int i=0; i<n; i++) {
  			for (int j=i+1; j<=n; j++) {
  				t = s.substring(i, j);
  				b = h.add(t);
  //				System.out.println(t + "	"  + b);
  				if (b==false) {
  					if (j-i>lmax) {
  						lmax = j-i;
  //						System.out.println(t);
  					}
  				}
  			}
  		}
  		System.out.println(lmax);
  	}
  }
  