source_code: import java.util.Scanner;
  
  
  public class P23A {
  	public static void main(String[] args) {
  		Scanner scan = new Scanner(System.in);
  		String input = scan.nextLine();
  		System.out.println(F(input));
  	}
  	
  	
  	static int F(String string){
  		int ans =0;
  		for (int i = 0; i < string.length(); i++) {
  			for (int j = 1; j < string.length()-i; j++) {
  				String s = string.substring(i, i+j);
  				int a=string.indexOf(s);
  				int b=string.lastIndexOf(s);
  				if ( a >= 0 && b >=0 && a !=b)  ans =Math.max(ans, s.length());
  			}
  		}
  		return ans;
  	}
  }
  