source_code: import java.io.*;
  import java.math.*;
  import java.util.*;
  
  public class StringRepeat
  {
  	static Scanner in = new Scanner( new BufferedReader( new InputStreamReader( System.in ) ) );
  
  	public static void main( String[] args )
  	{
  		String s = in.next();
  		int n = s.length(), ans = 0;
  		for( int i = 0; i < n; i++ ) for( int j = i+1; j < n; j++ )
  		{
  			int l = 0;
  			while( j+l<n && s.charAt(i+l)==s.charAt(j+l) ) l++;
  			ans = Math.max( ans, l );
  		}
  		System.out.println( ans );
  	}
  }
  