source_code: import java.io.*;
  import java.math.BigInteger;
  
  public class Main {
  	BufferedReader in;
  	PrintWriter out;
  	
  	public static void main(String[] args) throws IOException
  	{
  		new Main().run();
  	}
  	public void run() throws IOException
  	{
  		//in=new BufferedReader(new FileReader("input.txt"));
  		//out=new PrintWriter(new FileWriter("output.txt"));
  		in=new BufferedReader(new InputStreamReader(System.in));
  		out=new PrintWriter(new OutputStreamWriter(System.out));
  		solve();
  		
  		out.flush();
  	}
  
  	public void solve() throws IOException
  	{
  		String now=in.readLine();
  		int l=now.length();
  		int answ=0;
  		for(int i=0;i!=l;i++)
  			for(int j=i+1;j<l;j++)
  			{
  				String a=now.substring(i, j);
  				for(int k=i+1;k<l-j+i+1;k++)
  					if(a.compareTo(now.substring(k, k+j-i))==0)
  						answ=Math.max(answ, a.length());
  			}
  		out.print(answ);
  		
  		
  	}
  }
  