source_code: import java.util.Scanner;
  
  
  public class P23A {
  
  	public static void main(String[] args) {
  
  		Scanner in = new Scanner(System.in);
  		String s = in.nextLine();
  		int max = 0;
  		for(int i = 0; i < s.length(); i++)
  			for(int k = s.length(); k > max + i; k--)
  				if(s.substring(i + 1).contains(s.substring(i,k)))
  					max = k - i; 
  		System.out.println(max);
  	}
  
  }
  