source_code: import java.util.Scanner;
  
  public class Main{
  	public static void main(String args[]){
  		Scanner cin = new Scanner(System.in);
  		String str;
  		int i,j,k;
  		int cnt = 0;
  		char [] strArray;
  		
  		str = cin.next();
  		strArray = str.toCharArray();
  		
  		for(i = 0; i < strArray.length; i ++)
  			for(j = i + 1; j < strArray.length; j ++)
  			{
  				for(k = 0; (((i + k) < strArray.length && (j + k) < strArray.length) && (strArray[i + k] == strArray[j + k])); k ++)
  					if(k + 1> cnt) cnt = k + 1;
  			}
  		
  		System.out.println(cnt);
  	}
  }
  			 		 	 	 	  	  	 	 		 	